JOBS4TIMES

INTRODUCTION

• Data Definition Language (DDL)
• Data Manipulation Language (DML)
• Data Retrieval Language (DRL)
• Transaction Control Language (TCL)
• Data Control Language (DCL)

DDL -- create, alter, drop, truncate, rename
DML -- insert, update, delete
DRL -- select
TCL -- commit, rollback, savepoint
DCL -- grant, revoke

CREATE TABLE

SYNTAX :

Ex:
SQL> create table student (no number (2), name varchar (10), marks number (3));

INSERT

• By value method
• By address method

1. USING VALUE METHOD

   Syntax:
   insert into <table_name> values (value1, value2, value3 .... Valuen);

   Ex:
   SQL> insert into student values (1, 'sudha', 100);
   SQL> insert into student values (2, 'saketh', 200);

   To insert a new record again you have to type entire insert command, if there are lot of records this will be difficult.
   This will be avoided by using address method.
2. USING ADDRESS METHOD

   Syntax:
   insert into <table_name> values (&col1, &col2, &col3 .... &coln);

   This will prompt you for the values but for every insert you have to use forward slash.

   Ex:
   SQL> insert into student values (&no, '&name', &marks);

   Enter value for no: 1
   Enter value for name: Jagan
   Enter value for marks: 300
   old   1: insert into student values(&no, '&name', &marks)
   new   1: insert into student values(1, 'Jagan', 300)
   

   SQL> /

   Enter value for no: 2
   Enter value for name: Naren
   Enter value for marks: 400
   old   1: insert into student values(&no, '&name', &marks)
   new   1: insert into student values(2, 'Naren', 400)
   

3. INSERTING DATA INTO SPECIFIED COLUMNS USING VALUE METHOD

   Syntax:
   insert into <table_name>(col1, col2, col3 ... Coln) values (value1, value2, value3 ....Valuen);

   Ex:
   SQL> insert into student (no, name) values (3, 'Ramesh');
   SQL> insert into student (no, name) values (4, 'Madhu');

4. INSERTING DATA INTO SPECIFIED COLUMNS USING ADDRESS METHOD

   Syntax:
   insert into <table_name>(col1, col2, col3 ... coln) values (&col1, &col2, &col3 .... &coln);
   This will prompt you for the values but for every insert you have to use forward slash.

   Ex:
   SQL> insert into student (no, name) values (&no, '&name');

   Enter value for no: 5
   Enter value for name: Visu
   old   1:  insert into student (no, name) values(&no, '&name')
   new   1:  insert into student (no, name) values(5, 'Visu')
   

   SQL> /

   Enter value for no: 6
   Enter value for name: Rattu
   old   1:  insert into student (no, name) values(&no, '&name')
   new   1:  insert into student (no, name) values(6, 'Rattu')
   

SELECTING DATA

Syntax:
Select * from <table_name>;    -- here * indicates all columns
or
Select col1, col2, ... coln from <table_name>;

Ex:
SQL> select * from student;

    
        NO NAME                MARKS
        ---  ------           --------
         1   Sudha             100
         2   Saketh            200
         1   Jagan             300
         2   Naren             400
         3   Ramesh
         4   Madhu
         5   Visu
         6   Rattu

        NO NAME                MARKS
        ---  ------           --------
         1   Sudha             100
         2   Saketh            200
         1   Jagan             300
         2   Naren             400
         3   Ramesh
         4   Madhu
         5   Visu
         6   Rattu

         NO   NAME
        ---  -------
         1   Sudha
         2   Saketh
         1   Jagan
         2   Naren
         3   Ramesh
         4   Madhu
         5   Visu
         6   Rattu

CONDITIONAL SELECTIONS AND OPERATORS

• Where
• Order by

USING WHERE

Syntax:
select * from <table_name> where <condition>;

• Arithmetic operators
• Comparison operators
• Logical operators

• Arithmetic operators           -- highest precedence    +, -, *, /
• Comparison operators     =, !=, >, <, >=, <=, <>
  • between, not between
  • in, not in
  • null, not null
  • like
• Logical operators
  • And
  • Or                       -- lowest precedence
  • not

1. USING =, >, <, >=, <=, !=, <>

   Ex:
   SQL> select * from student where no = 2;

           NO NAME                MARKS
           ---  -------         ---------
            2   Saketh            200
            2   Naren             400
   

   SQL> select * from student where no < 2;

           NO NAME               MARKS
           ---  -------         ---------- 
            1   Sudha             100
            1   Jagan             300
   

   SQL> select * from student where no > 2;

    
            NO NAME                  MARKS
            ---  -------           ----------
            3   Ramesh
            4   Madhu
            5   Visu
            6   Rattu
   

   SQL> select * from student where no <= 2;

             NO  NAME             MARKS
            --- -------          ----------
            1   Sudha             100
            2   Saketh            200
            1   Jagan             300
            2   Naren             400
   

   SQL> select * from student where no >= 2;

            NO   NAME            MARKS
            --- -------          ---------
            2   Saketh            200
            2   Naren             400
            3   Ramesh
            4   Madhu
            5   Visu
            6   Rattu
   

   SQL> select * from student where no != 2;

            NO  NAME              MARKS
            --- -------          ----------
            1   Sudha             100
            1   Jagan             300
            3   Ramesh
            4   Madhu
            5   Visu
            6   Rattu
   

   SQL> select * from student where no <> 2;

            NO NAME            MARKS
            ---  -------           ----------
            1   Sudha             100
            1   Jagan             300
            3   Ramesh
            4   Madhu
            5   Visu
            6   Rattu
   

2. USING AND

   This will gives the output when all the conditions become true.

   Syntax:
   select * from <table_name> where <condition1> and <condition2> and .. <conditionn>;

   Ex:
   SQL> select * from student where no = 2 and marks >= 200;

            		      NO NAME            MARKS
            ---  -------           --------
            2   Saketh            200
            2   Naren             400
   

3. USING OR

   This will gives the output when either of the conditions become true.

   Syntax:
   select * from <table_name> where <condition1> and <condition2> or .. <conditionn>;

   Ex:
   SQL> select * from student where no = 2 or marks >= 200;

            NO NAME            MARKS
            ---  -------           ---------
            2   Saketh            200
            1   Jagan             300
            2   Naren             400
   

4. USING BETWEEN

   This will gives the output based on the column and its lower bound, upperbound.

   Syntax:
   select * from <table_name> where <col> between <lower bound> and <upper bound>;

   Ex:
   SQL> select * from student where marks between 200 and 400;

    
            NO NAME            MARKS
            ---  -------           ---------
            2   Saketh            200
            1   Jagan              300
            2   Naren              400
   

5. USING NOT BETWEEN

   This will gives the output based on the column which values are not in its lower bound, upperbound.

   Syntax:
   select * from <table_name> where <col> not between <lower bound> and <upper bound>;

   Ex:
   SQL> select * from student where marks not between 200 and 400;

            NO NAME            MARKS
            ---  -------           --------- 
            1   Sudha             100
   

6. USING IN

   This will gives the output based on the column and its list of values specified.

   Syntax:
   select * from <table_name> where <col> in ( value1, value2, value3 ... valuen);

   Ex:
   SQL> select * from student where no in (1, 2, 3);

            NO NAME            MARKS
            --- -------            ---------
            1   Sudha             100
            2   Saketh            200
            1   Jagan             300
            2   Naren             400
            3   Ramesh
   

7. USING NOT IN

   This will gives the output based on the column which values are not in the list of values specified.

   Syntax:
   select * from <table_name> where <col> not in ( value1, value2, value3 ... valuen);

   Ex:
   SQL> select * from student where no not in (1, 2, 3);

            NO NAME            MARKS
            ---  -------           ---------
            4   Madhu
            5   Visu
            6   Rattu
   

8. USING NULL

   This will gives the output based on the null values in the specified column.

   Syntax:
   select * from <table_name> where <col> is null;

   Ex:
   SQL> select * from student where marks is null;

            NO NAME            MARKS
            ---  -------           ---------
            3   Ramesh
            4   Madhu
            5   Visu
            6   Rattu
   

9. USING NOT NULL

   This will gives the output based on the not null values in the specified column.

   Syntax:
   select * from <table_name> where <col> is not null;

   Ex:
   SQL> select * from student where marks is not null;

            NO NAME            MARKS
            ---  -------           ---------
            1   Sudha             100
            2   Saketh            200
            1   Jagan             300
            2   Naren             400
   

10. USING LIKE

    This will be used to search through the rows of database column based on the pattern you specify.

    Syntax:
    select * from <table_name> where <col> like <pattern>;

    Ex:
    
    1. This will give the rows whose marks are 100.
       SQL> select * from student where marks like 100;

                NO NAME            MARKS
                ---  -------           ---------
                1   Sudha             100
       

    2. This will give the rows whose name start with 'S'.
       SQL> select * from student where name like 'S%';

                NO NAME            MARKS
                ---  -------           ---------
                1   Sudha             100
                2   Saketh            200
       

    3. This will give the rows whose name ends with 'h'.
       SQL> select * from student where name like '%h';

                 
                NO NAME            MARKS
                ---  -------           ---------
                2   Saketh            200
                3   Ramesh
       

    4. This will give the rows whose name's second letter start with 'a'.
       SQL> select * from student where name like '_a%';

                 NO NAME            MARKS
                 ---  -------            --------
                 2   Saketh            200
                 1   Jagan             300
                 2   Naren             400
                 3   Ramesh
                 4   Madhu
                 6   Rattu
       

    5. This will give the rows whose name's third letter start with 'd'.
       SQL> select * from student where name like '__d%';

                NO NAME            MARKS
                ---  -------           ---------
                1   Sudha             100
                4   Madhu
       

    6. This will give the rows whose name's second letter start with 't' from ending.
       SQL> select * from student where name like '%_t%';

                NO   NAME            MARKS
               ---  -------         ---------
                2   Saketh            200
                6   Rattu
       

    7. This will give the rows whose name's third letter start with 'e' from ending.
       SQL> select * from student where name like '%e__%';

                NO   NAME            MARKS
               ---  -----           ---------
                2   Saketh            200
                3   Ramesh
       

    8. This will give the rows whose name cotains 2 a's.
       SQL> select * from student where name like '%a% a %';

                NO  NAME            MARKS
               --- -------         ---------- 
                1   Jagan             300
       

    * You have to specify the patterns in like using underscore ( _ ).

USING ORDER BY

Syntax:
Select * from <table_name> order by <col> desc;

Ex:
SQL> select * from student order by no;

        NO    NAME            MARKS
        ---  -------         ---------
         1   Sudha             100
         1   Jagan              300
         2   Saketh            200
         2   Naren             400
         3   Ramesh
         4   Madhu
         5   Visu
         6   Rattu

         NO NAME            MARKS
        --- -------           ---------
         6 Rattu
         5 Visu
         4 Madhu
         3 Ramesh
         2 Saketh            200
         2 Naren             400
         1 Sudha             100
         1 Jagan             300
         

USING DML

USING UPDATE

Syntax:
Update <table_name> set <col1> = value1, <col2> = value2 where <condition>;

Ex:
SQL> update student set marks = 500;

SQL> update student set marks = 500 where no = 2;

SQL> update student set marks = 500, name = 'Venu' where no = 1;

USING DELETE

Syntax:
Delete <table_name> where <condition>;

Ex:
SQL> delete student;

SQL> delete student where no = 2;

USING DDL

USING ALTER

1. ADDING COLUMN

   Syntax:
   alter table <table_name> add <col datatype>;

   Ex:
   SQL> alter table student add sdob date;

2. REMOVING COLUMN

   Syntax:
   alter table <table_name> drop <col datatype>;

   Ex:
   SQL> alter table student drop column sdob;

3. INCREASING OR DECREASING PRECISION OF A COLUMN

   Syntax:
   alter table <table_name> modify <col datatype>;

   Ex:
   SQL> alter table student modify marks number(5);

   * To decrease precision the column should be empty.
4. MAKING COLUMN UNUSED

   Syntax:
   alter table <table_name> set unused column <col>;

   Ex:
   SQL> alter table student set unused column marks;

   Even though the column is unused still it will occupy memory.
5. DROPPING UNUSED COLUMNS

   Syntax:
   alter table <table_name> drop unused columns;

   Ex:
   SQL> alter table student drop unused columns;

   * You can not drop individual unused columns of a table.
6. RENAMING COLUMN

   Syntax:
   alter table <table_name> rename column <old_col_name> to <new_col_name>;

   Ex:
   SQL> alter table student rename column marks to smarks;

USING TRUNCATE

Syntax:
truncate table <table_name>;

Ex:
SQL> truncate table student;

USING DROP

Syntax:
Drop table <table_name>;

Ex:
SQL> drop table student;

USING RENAME

Syntax:
rename <old_table_name> to <new_table_name>;

Ex:
SQL> rename student to stud;

USING TCL

USING COMMIT

• Implicit
• Explicit

1. IMPLICIT

   This will be issued by oracle internally in two situations.

   • When any DDL operation is performed.
   • When you are exiting from SQL * PLUS.
2. EXPLICIT

   This will be issued by the user.

   Syntax:
   Commit or commit work;

   * When ever you committed then the transaction was completed.

USING ROLLBACK

• Upto previous commit
• Upto previous rollback

Syntax:
Roll or roll work;

Rollback or rollback work;

USING SAVEPOINT

Syntax:
Savepoint <savepoint_name>;

Ex: 
     SQL> savepoint s1;
     SQL> insert into student values(1, 'a', 100);
     SQL> savepoint s2;
     SQL> insert into student values(2, 'b', 200);
     SQL> savepoint s3;
      SQL> insert into student values(3, 'c', 300);
     SQL> savepoint s4;
      SQL> insert into student values(4, 'd', 400);

        NO NAME      MARKS
        ---  -------     ----------
         1 	a         100
         2 	b         200
         3 	c         300
         4 	d         400

This will rollback last two records.

        NO NAME      MARKS
        ---  -------     ----------
         1 	a         100
         2 	b         200

USING DCL

USING GRANT

Syntax:
Grant <privileges> on <object_name> to <user_name> [with grant option];

SQL> grant select on student to sudha; -- you can give individual privilege

SQL> grant select, insert on student to sudha; -- you can give set of privileges

The sudha user has to use dot method to access the object.
SQL> select * from saketh.student;

The sudha user can not grant permission on student table to other users. To get this type of option use the following.
SQL> grant all on student to sudha with grant option;

USING REVOKE

Syntax:
Revoke <privileges> on <object_name> from <user_name>;

SQL> revoke select on student form sudha; -- you can revoke individual privilege

SQL> revoke select, insert on student from sudha; -- you can revoke set of privileges

USING ALIASES

CREATE WITH SELECT

Syntax:
Create table <new_table_name> [col1, col2, col3 ... coln] as select * from <old_table_name>;

Creating table with your own column names.
SQL> create table student2(sno, sname, smarks) as select * from student;

Creating table with specified columns.
SQL> create table student3 as select no,name from student;

Creating table with out table data.
SQL> create table student2(sno, sname, smarks) as select * from student where 1 = 2;

INSERT WITH SELECT

Syntax:
Insert into <table1> select * from <table2>;

Ex:
SQL> insert into student1 select * from student;

Inserting data into specified columns
SQL> insert into student1(no, name) select no, name from student;

COLUMN ALIASES

Syntax:
Select <orginal_col> <alias_name> from <table_name>;

Ex:
SQL> select no sno from student;      or
SQL> select no "sno" from student;

TABLE ALIASES

Syntax:
Select <alias_name>.<col1>, <alias_name>.<col2> ... <alias_name>.<coln> from <table_name> <alias_name>;

Ex:
SQL> select s.no, s.name from student s;

USING MERGE

MERGE

SQL> Merge into student1 s1
        Using (select *From student2) s2
        On(s1.no=s2.no)
        When matched then
        Update set marks = s2.marks
        When not matched then
        Insert (s1.no,s1.name,s1.marks)
        Values(s2.no,s2.name,s2.marks);

Assume that student1 has columns like no,name,marks and student2 has columns like no, name, hno, city.

SQL> Merge into student1 s1
        Using (select *From student2) s2
        On(s1.no=s2.no)
        When matched then
        Update set marks = s2.hno
        When not matched then
        Insert (s1.no,s1.name,s1.marks)
        Values(s2.no,s2.name,s2.hno);

MULTIBLE INSERTS

DEPTNO	DNAME	LOC
--------	--------	----
10		accounting	new york
20		research 	dallas
30		sales 		Chicago
40		operations	boston

1. CREATE STUDENT TABLE
   SQL> Create table student(no number(2),name varchar(2),marks number(3));
2. MULTI INSERT WITH ALL FIELDS

        SQL> Insert all
                Into student values(1,'a',100)
                Into student values(2,'b',200)
                Into student values(3,'c',300)
                Select *from dept where deptno=10;
   

   -- This inserts 3 rows
3. MULTI INSERT WITH SPECIFIED FIELDS

        SQL> insert all
                Into student (no,name) values(4,'d')
                Into student(name,marks) values('e',400)
                Into student values(3,'c',300)
                Select *from dept where deptno=10;
   

   -- This inserts 3 rows
4. MULTI INSERT WITH DUPLICATE ROWS

        SQL> insert all
                Into student values(1,'a',100)
                Into student values(2,'b',200)
                Into student values(3,'c',300)
                Select *from dept where deptno > 10;
   

   -- This inserts 9 rows because in the select statement retrieves 3 records (3 inserts for each row retrieved)
5. MULTI INSERT WITH CONDITIONS BASED

        SQL> Insert all
                When deptno > 10 then
                Into student1 values(1,'a',100)
                When dname = 'SALES' then
                Into student2 values(2,'b',200)
                When loc = 'NEW YORK' then
                Into student3 values(3,'c',300)
                Select *from dept where deptno>10;
   

   -- This inserts 4 rows because the first condition satisfied 3 times, second condition satisfied once and the last none.
6. MULTI INSERT WITH CONDITIONS BASED AND ELSE

       SQL> Insert all
               When deptno > 100 then
               Into student1 values(1,'a',100)
               When dname = 'S' then
               Into student2 values(2,'b',200)
               When loc = 'NEW YORK' then
               Into student3 values(3,'c',300)
               Else 
               Into student values(4,'d',400)
               Select *from dept where deptno>10;
   

   -- This inserts 3 records because the else satisfied 3 times
7. MULTI INSERT WITH CONDITIONS BASED AND FIRST

        SQL> Insert first
                When deptno = 20 then
                Into student1 values(1,'a',100)
                When dname = 'RESEARCH' then
                Into student2 values(2,'b',200)
                When loc = 'NEW YORK' then
                Into student3 values(3,'c',300)
                Select *from dept where deptno=20;
   

   -- This inserts 1 record because the first clause avoid to check the remaining conditions once the condition is satisfied.
8. MULTI INSERT WITH CONDITIONS BASED, FIRST AND ELSE

        SQL> Insert first
                When deptno = 30 then
                 Into student1 values(1,'a',100)
                 When dname = 'R' then
                 Into student2 values(2,'b',200)
                 When loc = 'NEW YORK' then
                 Into student3 values(3,'c',300)
                 Else
                 Into student values(4,'d',400)
                 Select *from dept where deptno=20;
   

   -- This inserts 1 record because the else clause satisfied once
9. MULTI INSERT WITH MULTIBLE TABLES

       SQL> Insert all
               Into student1 values(1,'a',100)
               Into student2 values(2,'b',200)
               Into student3 values(3,'c',300)
               Select *from dept where deptno=10;
   

   -- This inserts 3 rows

** You can use multi tables with specified fields, with duplicate rows, with conditions, with first and else clauses.

FUNCTIONS

• Single row functions
• Group functions

SINGLE ROW FUNCTIONS

• Numeric functions
• String functions
• Date functions
• Miscellaneous functions
• Conversion functions

NUMERIC FUNCTIONS

• Abs
• Sign
• Sqrt
• Mod
• Nvl
• Power
• Exp
• Ln
• Log
• Ceil
• Floor
• Round
• Trunk
• Bitand
• Greatest
• Least
• Coalesce

1. ABS
   Absolute value is the measure of the magnitude of value. Absolute value is always a positive number.

   Syntax:
   abs (value)

   Ex:
   SQL> select abs(5), abs(-5), abs(0), abs(null) from dual;

   ABS(5)    ABS(-5)     ABS(0)  ABS(NULL)
   ------    -------     ------  ---------
    5        -5           0
   

2. SIGN
   Sign gives the sign of a value.

   Syntax:
   sign (value)

   Ex:
   SQL> select sign(5), sign(-5), sign(0), sign(null) from dual;

   SIGN(5)   SIGN(-5)    SIGN(0) SIGN(NULL)
   -------   --------    ------- ----------
    1         -1          	0
   

3. SQRT
   This will give the square root of the given value.

   Syntax:
   sqrt (value) -- here value must be positive.

   Ex:
   SQL> select sqrt(4), sqrt(0), sqrt(null), sqrt(1) from dual;

   SQRT(4)    SQRT(0) SQRT(NULL)    SQRT(1)
   -------    ------- ----------    ----------
    2           0                     1
   

4. MOD
   This will give the remainder.

   Syntax:
   mod (value, divisor)

   Ex:
   SQL> select mod(7,4), mod(1,5), mod(null,null), mod(0,0), mod(-7,4) from dual;

   MOD(7,4)   MOD(1,5) MOD(NULL,NULL)   MOD(0,0)  MOD(-7,4)
   --------   -------- --------------   --------  ---------
    3          1                         0        	-3
   

5. NVL
   This will substitutes the specified value in the place of null values.

   Syntax:
   nvl (null_col, replacement_value)

   Ex:
   SQL> select * from student; -- here for 3rd row marks value is null

   NO   NAME      MARKS
   --   ----      ---------
   1    a         100
   2    b         200
   3    c
   

   SQL> select no, name, nvl(marks,300) from student;

   NO  NAME      NVL(MARKS,300)
   --  ----      --------------
   1  	a             100
   2 	b             200
   3 	c             300
   

   SQL> select nvl(1,2), nvl(2,3), nvl(4,3), nvl(5,4) from dual;

     NVL(1,2)   NVL(2,3)   NVL(4,3)   NVL(5,4)
     --------   --------   --------   --------
      1          2            4        5
   

   SQL> select nvl(0,0), nvl(1,1), nvl(null,null), nvl(4,4) from dual;

     
     NVL(0,0)   NVL(1,1) NVL(null,null)  NVL(4,4)
     --------   -------- --------------  ----------
       0          1                        4
   

6. POWER
   Power is the ability to raise a value to a given exponent.

   Syntax:
   power (value, exponent)

   Ex:
   SQL> select power(2,5), power(0,0), power(1,1), power(null,null), power(2,-5) from dual;

   POWER(2,5) POWER(0,0) POWER(1,1) POWER(NULL,NULL) POWER(2,-5)
   ---------- ---------- --------- ----------------- ---------------
    32         1           1                       	.03125
   

7. EXP
   This will raise e value to the give power.

   Syntax:
   exp (value)

   Ex:
   SQL> select exp(1), exp(2), exp(0), exp(null), exp(-2) from dual;

   EXP(1)     	EXP(2)    EXP(0)    EXP(NULL)    EXP(-2)
   --------    ---------   ------    ---------    ----------
   2.71828183  7.3890561     1                    .135335283
   

8. LN
   This is based on natural or base e logarithm.

   Syntax:
   ln (value) -- here value must be greater than zero which is positive only.

   Ex:
   SQL> select ln(1), ln(2), ln(null) from dual;

    LN(1)      LN(2)      LN(NULL)
    ------    -------     ------------
     0 	   .693147181
   

   Ln and Exp are reciprocal to each other.
   EXP (3) = 20.0855369
   LN (20.0855369) = 3
9. LOG
   This is based on 10 based logarithm.

   Syntax:
   log (10, value) -- here value must be greater than zero which is positive only.

   Ex:
   SQL> select log(10,100), log(10,2), log(10,1), log(10,null) from dual;

   LOG(10,100)  LOG(10,2)   LOG(10,1) LOG(10,NULL)
   -----------  ----------- --------- -----------------
     2          .301029996     0
   

   LN (value) = LOG (EXP(1), value)
   SQL> select ln(3), log(exp(1),3) from dual;

     LN(3)      LOG(EXP(1),3)
   -------      -----------------
   1.09861229    1.09861229
   

10. CEIL
    
    This will produce a whole number that is greater than or equal to the specified value.

    Syntax:
    ceil (value)

    Ex:
    SQL> select ceil(5), ceil(5.1), ceil(-5), ceil( -5.1), ceil(0), ceil(null) from dual;

    CEIL(5)  CEIL(5.1)  CEIL(-5) CEIL(-5.1)  CEIL(0) CEIL(NULL)
    -------  ---------  -------- ----------  ------- ----------
      5        6          -5       -5          0
    

11. FLOOR
    This will produce a whole number that is less than or equal to the specified value.

    Syntax:
    floor (value)

    Ex:
    SQL> select floor(5), floor(5.1), floor(-5), floor( -5.1), floor(0), floor(null) from dual;

    FLOOR(5) FLOOR(5.1)  FLOOR(-5) FLOOR(-5.1)   FLOOR(0) FLOOR(NULL)
    -------- ----------  --------  -----------  --------- ----------- 
      5        5          -5          -6           0
    

12. ROUND
    This will rounds numbers to a given number of digits of precision.

    Syntax:
    round (value, precision)

    Ex:
    SQL> select round(123.2345), round(123.2345,2), round(123.2354,2) from dual;

    ROUND(123.2345)  ROUND(123.2345,0) ROUND(123.2345,2) ROUND(123.2354,2)
    ---------------  ----------------- ----------------- -----------------
      123              123               123.23            123.24
    

    SQL> select round(123.2345,-1), round(123.2345,-2), round(123.2345,-3), round(123.2345,-4) from dual;

        
    ROUND(123.2345,-1) ROUND(123.2345,-2) ROUND(123.2345,-3) ROUND(123.2345,-4)
    ------------------ ------------------ ------------------ ------------------
      120                100                  0           		0
    

    SQL> select round(123,0), round(123,1), round(123,2) from dual;

    ROUND(123,0) ROUND(123,1) ROUND(123,2)
    -----------  ------------ ------------
      123          123  		123
    

    SQL> select round(-123,0), round(-123,1), round(-123,2) from dual;

    ROUND(-123,0) ROUND(-123,1) ROUND(-123,2)
    ------------  ------------- -------------
     -123          -123          -123
    

    SQL> select round(123,-1), round(123,-2), round(123,-3), round(-123,-1), round(-123,- 2), round(-123,-3) from dual;

    		
    ROUND(123,-1) ROUND(123,-2) ROUND(123,-3) ROUND(-123,-1) ROUND(-123,-2) ROUND(-123,-3)
    ------------- ------------- ------------- -------------- -------------- --------------
       120         100            0              -120             -100            0
    

    SQL> select round(null,null), round(0,0), round(1,1), round(-1,-1), round(-2,-2) from dual;

    ROUND(NULL,NULL) ROUND(0,0) ROUND(1,1) ROUND(-1,-1) ROUND(-2,-2)
    ---------------- ---------- ---------- ------------ ------------
                        0           1          0            0
    

13. TRUNC
    This will truncates or chops off digits of precision from a number.

    Syntax:
    trunc (value, precision)

    Ex:
    SQL> select trunc(123.2345), trunc(123.2345,2), trunc(123.2354,2) from dual;

    TRUNC(123.2345) TRUNC(123.2345,2) TRUNC(123.2354,2)
    --------------- ----------------- -----------------
          123         123.23             123.23 
    

    SQL> select trunc(123.2345,-1), trunc(123.2345,-2), trunc(123.2345,-3), trunc(123.2345,-4) from dual;

    		 
    TRUNC(123.2345,-1) TRUNC(123.2345,-2) TRUNC(123.2345,-3) TRUNC(123.2345,-4)
    ------------------ ------------------ ------------------ ------------------
        120               100                0                   0
    

    SQL> select trunc(123,0), trunc(123,1), trunc(123,2) from dual;

    TRUNC(123,0) TRUNC(123,1) TRUNC(123,2)
    ------------ ------------ -----------
       123         123          123
    

    SQL> select trunc(-123,0), trunc(-123,1), trunc(-123,2) from dual;

    TRUNC(-123,0) TRUNC(-123,1) TRUNC(-123,2)
    ------------- ------------- -------------
     -123           -123          -123
    

    SQL> select trunc(123,-1), trunc(123,-2), trunc(123,-3), trunc(-123,-1), trunc(-123,2), trunc(-123,-3) from dual;

    		 
    TRUNC(123,-1) TRUNC(123,-2) TRUNC(123,-3) TRUNC(-123,-1) TRUNC(-123,2) TRUNC(-123,-3)
    ------------- ------------- ------------- -------------- ------------- --------------
        120           100             0           -120          -123              0
    

    SQL> select trunc(null,null), trunc(0,0), trunc(1,1), trunc(-1,-1), trunc(-2,-2) from dual;

    TRUNC(NULL,NULL) TRUNC(0,0) TRUNC(1,1) TRUNC(-1,-1) TRUNC(-2,-2)
    ---------------- ---------- ---------- ------------ ----------------
                       0            1          0             0
    

14. BITAND
    This will perform bitwise and operation.

    Syntax:
    bitand (value1, value2)

    Ex:
    SQL> select bitand(2,3), bitand(0,0), bitand(1,1), bitand(null,null), bitand(-2,-3) from dual;

    		  
    BITAND(2,3) BITAND(0,0) BITAND(1,1)  BITAND(NULL,NULL) BITAND(-2,-3)
    ----------- ----------  -----------   ---------------- -------------
       2           	0           1                              -4
    

15. GREATEST
    This will give the greatest number.

    Syntax:
    greatest (value1, value2, value3 ... valuen)

    Ex:
    SQL> select greatest(1, 2, 3), greatest(-1, -2, -3) from dual;

    GREATEST(1,2,3) GREATEST(-1,-2,-3)
    --------------- ------------------
         3                 	-1
    

    • If all the values are zeros then it will display zero.
    • If all the parameters are nulls then it will display nothing.
    • If any of the parameters is null it will display nothing.
16. LEAST
    This will give the least number.

    Syntax:
    least (value1, value2, value3 ... valuen)

    Ex:
    SQL> select least(1, 2, 3), least(-1, -2, -3) from dual;

    LEAST(1,2,3)    LEAST(-1,-2,-3)
    ------------    ---------------
         1             	-3
    

    • If all the values are zeros then it will display zero.
    • If all the parameters are nulls then it will display nothing.
    • If any of the parameters is null it will display nothing.
17. COALESCE
    This will return first non-null value.

    Syntax:
    coalesce (value1, value2, value3 ... valuen)

    Ex:
    SQL> select coalesce(1,2,3), coalesce(null,2,null,5) from dual;

    COALESCE(1,2,3)     COALESCE(NULL,2,NULL,5)
    ---------------     -----------------------
         1                       2
    

STRING FUNCTIONS

• Initcap
• Upper
• Lower
• Length
• Rpad
• Lpad
• Ltrim
• Rtrim
• Trim
• Translate
• Replace
• Soundex
• Concat ( ' || ' Concatenation operator)
• Ascii
• Chr
• Substr
• Instr
• Decode
• Greatest
• Least
• Coalesce

1. INITCAP
   This will capitalize the initial letter of the string.

   Syntax:
   initcap (string)

   Ex:
   SQL> select initcap('computer') from dual;

   INITCAP
   --------
   Computer
   

2. UPPER
   This will convert the string into uppercase.

   Syntax:
   upper (string)

   Ex:
   SQL> select upper('computer') from dual;

   UPPER
   ---------
   COMPUTER
   

3. LOWER
   This will convert the string into lowercase.

   Syntax:
   lower (string)

   Ex:
   SQL> select lower('COMPUTER') from dual;

   LOWER
   ---------
   computer
   

4. LENGTH
   This will give length of the string.

   Syntax:
   length (string)

   Ex:
   SQL> select length('computer') from dual;

   LENGTH
   -------
     8
   

5. RPAD
   This will allows you to pad the right side of a column with any set of characters.

   Syntax:
   rpad (string, length [, padding_char])

   Ex:
   SQL> select rpad('computer',15,'*'), rpad('computer',15,'*#') from dual;

   RPAD('COMPUTER'    RPAD('COMPUTER'
   ---------------    ----------------
   computer*******     computer*#*#*#*
   

   -- Default padding character was blank space.
6. LPAD
   This will allows you to pad the left side of a column with any set of characters.

   Syntax:
   lpad (string, length [, padding_char])

   Ex:
   SQL> select lpad('computer',15,'*'), lpad('computer',15,'*#') from dual;

   LPAD('COMPUTER'    LPAD('COMPUTER'
   ---------------   ------------------
   *******computer     *#*#*#*computer
   

   -- Default padding character was blank space.
7. LTRIM
   This will trim off unwanted characters from the left end of string.

   Syntax:
   ltrim (string [,unwanted_chars])

   Ex:
   SQL> select ltrim('computer','co'), ltrim('computer','com') from dual;

   LTRIM(     LTRIM
   --------  ---------
   mputer     puter
   

   SQL> select ltrim('computer','puter'), ltrim('computer','omputer') from dual;

   LTRIM('C     LTRIM('C
   ----------   ----------
   computer      computer
   

   -- If you haven't specify any unwanted characters it will display entire string.
8. RTRIM
   This will trim off unwanted characters from the right end of string.

   Syntax:
   rtrim (string [, unwanted_chars])

   Ex:
   SQL> select rtrim('computer','er'), rtrim('computer','ter') from dual;

   RTRIM(     RTRIM
   --------  ---------
   comput     compu
   

   SQL> select rtrim('computer','comput'), rtrim('computer','compute') from dual;

   RTRIM('C     RTRIM('C
   ----------   ----------
   computer     computer
   

   -- If you haven't specify any unwanted characters it will display entire string.
9. TRIM
   This will trim off unwanted characters from the both sides of string.

   Syntax:
   trim (unwanted_chars from string)

   Ex:
   SQL> select trim( 'i' from 'indiani') from dual;

   TRIM(
   -----
   ndian
   

   SQL> select trim( leading'i' from 'indiani') from dual; -- this will work as LTRIM

   TRIM(L
   ------
   ndiani
   

   SQL> select trim( trailing'i' from 'indiani') from dual; -- this will work as RTRIM

   TRIM(T
   ------
   Indian
   

10. TRANSLATE
    This will replace the set of characters, character by character.

    Syntax:
    translate (string, old_chars, new_chars)

    Ex:
    SQL> select translate('india','in','xy') from dual;

    TRANS
    --------
    xydxa
    

11. REPLACE
    This will replace the set of characters, string by string.

    Syntax:
    replace (string, old_chars [, new_chars])

    Ex:
    SQL> select replace('india','in','xy'), replace('india','in') from dual;

    REPLACE   	REPLACE
    -----------  -----------
    Xydia         dia
    

12. SOUNDEX
    This will be used to find words that sound like other words, exclusively used in where clause.

    Syntax:
    soundex (string)

    Ex:
    SQL> select * from emp where soundex(ename) = soundex('SMIT');

    EMPNO  ENAME    JOB      MGR    HIREDATE      SAL     DEPTNO
    -----  ------  -----     ----  ------------   -----  --------
    7369   SMITH   CLERK     7902   17-DEC-80      500     20
    

13. CONCAT
    This will be used to combine two strings only.

    Syntax:
    concat (string1, string2)

    Ex:
    SQL> select concat('computer',' operator') from dual;

    CONCAT('COMPUTER'
    ------------------
    computer operator
    

    If you want to combine more than two strings you have to use concatenation operator (||).

    SQL> select 'how' || ' are' || ' you' from dual;

    		 
    'HOW'||'ARE
    ------------
    how are you
    

14. ASCII
    This will return the decimal representation in the database character set of the first character of the string.

    Syntax:
    ascii (string)

    Ex:
    SQL> select ascii('a'), ascii('apple') from dual;

    ASCII('A')  ASCII('APPLE')
    ------------  ------------
          97         97
    

15. CHR
    This will return the character having the binary equivalent to the string in either the database character set or the national character set.

    Syntax:
    chr (number)

    Ex:
    SQL> select chr(97) from dual;

    CHR
    -----
       a
    

16. SUBSTR
    This will be used to extract substrings.

    Syntax:
    substr (string, start_chr_count [, no_of_chars])

    Ex:
    SQL> select substr('computer',2), substr('computer',2,5), substr('computer',3,7) from dual;

    SUBSTR(     SUBST  	 SUBSTR
    --------   -------   --------
    omputer     omput     mputer
    

    • If no_of_chars parameter is negative then it will display nothing.
    • If both parameters except string are null or zeros then it will display nothing.
    • If no_of_chars parameter is greater than the length of the string then it ignores and calculates based on the orginal string length.
    • If start_chr_count is negative then it will extract the substring from right end.

    
    1	2	3	4	5	6	7	8
    
    C	O	M	P	U	T	E	R
    
    -8	-7	-6	-5	-4	-3	-2	-1
    
    

17. INSTR
    This will allows you for searching through a string for set of characters.

    Syntax:
    instr (string, search_str [, start_chr_count [, occurrence] ])

    Ex:
    SQL> select instr('information','o',4,1), instr('information','o',4,2) from dual;

    INSTR('INFORMATION','O',4,1)          INSTR('INFORMATION','O',4,2)
    ---------------------------           ----------------------------
             4                           		10
    

    • If you are not specifying start_chr_count and occurrence then it will start search from the beginning and finds first occurrence only.
    • If both parameters start_chr_count and occurrence are null, it will display nothing.
18. DECODE
    Decode will act as value by value substitution. For every value of field, it will checks for a match in a series of if/then tests.

    Syntax:
    decode (value, if1, then1, if2, then2, ....... else);

    Ex:
    SQL> select sal, decode(sal,500,'Low',5000,'High','Medium') from emp;

           SAL     DECODE
          -----    ---------
           500 	 Low
          2500	 Medium
          2000 	Medium
          3500 	Medium
          3000 	Medium
          5000 	High
          4000 	Medium
          5000 	High
          1800 	Medium
          1200 	Medium
          2000 	Medium
          2700 	Medium
          2200 	Medium
          3200 	Medium  
    

    SQL> select decode(1,1,3), decode(1,2,3,4,4,6) from dual;

    DECODE(1,1,3) 	        DECODE(1,2,3,4,4,6)
    -----------------  ------------------------
                3                   	6
    

    • If the number of parameters are odd and different then decode will display nothing.
    • If the number of parameters are even and different then decode will display last value.
    • If all the parameters are null then decode will display nothing.
    • If all the parameters are zeros then decode will display zero.
19. GREATEST
    This will give the greatest string.

    Syntax:
    greatest (strng1, string2, string3 ... stringn)

    Ex:
    SQL> select greatest('a', 'b', 'c'), greatest('satish','srinu','saketh') from dual;

    GREAT 	  GREAT
    -------  -------
        c 	   srinu
    

    • If all the parameters are nulls then it will display nothing.
    • If any of the parameters is null it will display nothing.
20. LEAST
    This will give the least string.

    Syntax:
    greatest (strng1, string2, string3 ... stringn)

    Ex:
    SQL> select least('a', 'b', 'c'), least('satish','srinu','saketh') from dual;

    LEAST 	   LEAST
    -------  -------
        a 	   saketh
    

    • If all the parameters are nulls then it will display nothing.
    • If any of the parameters is null it will display nothing.
21. COALESCE
    This will gives the first non-null string.

    Syntax:
    coalesce (strng1, string2, string3 ... stringn)

    Ex:
    SQL> select coalesce('a','b','c'), coalesce(null,'a',null,'b') from dual;

    COALESCE 	COALESCE
    -----------   -----------
           a           a
    

DATE FUNCTIONS

• Sysdate
• Current_date
• Current_timestamp
• Systimestamp
• Localtimestamp
• Dbtimezone
• Sessiontimezone
• To_char
• To_date
• Add_months
• Months_between
• Next_day
• Last_day
• Extract
• Greatest
• Least
• Round
• Trunc
• New_time
• Coalesce

Oracle default date format is DD-MON-YY.

SQL> alter session set nls_date_format = 'DD-MONTH-YYYY';
But this will expire once the session was closed.

1. SYSDATE
   This will give the current date and time.

   Ex:
   SQL> select sysdate from dual;

   SYSDATE
   -----------
   24-DEC-06
   

2. CURRENT_DATE
   This will returns the current date in the session's timezone.

   Ex:
   SQL> select current_date from dual;

   CURRENT_DATE
   ------------------
        24-DEC-06
   

3. CURRENT_TIMESTAMP
   This will returns the current timestamp with the active time zone information.

   Ex:
   SQL> select current_timestamp from dual;

   CURRENT_TIMESTAMP
   -----------------------------------------
   24-DEC-06 03.42.41.383369 AM +05:30
   

4. SYSTIMESTAMP
   This will returns the system date, including fractional seconds and time zone of the database.

   Ex:
   SQL> select systimestamp from dual;

   		   
   SYSTIMESTAMP
   ------------------------------------
   24-DEC-06 03.49.31.830099 AM +05:30
   

5. LOCALTIMESTAMP
   This will returns local timestamp in the active time zone information, with no time zone information shown.

   Ex:
   SQL> select localtimestamp from dual;

   LOCALTIMESTAMP
   -----------------------------
   24-DEC-06 03.44.18.502874 AM
   

6. DBTIMEZONE
   This will returns the current database time zone in UTC format. (Coordinated Universal Time)

   Ex:
   SQL> select dbtimezone from dual;

   DBTIMEZONE
   ---------------
      -07:00  
   

7. SESSIONTIMEZONE
   This will returns the value of the current session's time zone.

   Ex:
   SQL> select sessiontimezone from dual;

   SESSIONTIMEZONE
   ----------------
   +05:30
   

8. TO_CHAR
   This will be used to extract various date formats. The available date formats as follows.

   Syntax:
   to_char (date, format)

   DATE FORMATS

     
   	D		--	No of days in week
   	DD		--	No of days in month
   	DDD		--	No of days in year
   	MM		--	No of month
   	MON		--	Three letter abbreviation of month
   	MONTH 	--	Fully spelled out month
   	RM		-- 	Roman numeral month
   	DY		--	Three letter abbreviated day
   	DAY		--	Fully spelled out day
   	Y		--	Last one digit of the year
   	YY		--	Last two digits of the year
   	YYY		--	Last three digits of the year
   	YYYY		--	Full four digit year
   	SYYYY	--	Signed year
   	I		--	One digit year from ISO standard
   	IY		--	Two digit year from ISO standard
   	IYY		--	Three digit year from ISO standard
   	IYYY		--	Four digit year from ISO standard
   	Y, YYY		--	Year with comma
   	YEAR		--	Fully spelled out year
   	CC		--	Century
   	Q		--	No of quarters
   	W		--	No of weeks in month
   	WW		-- 	No of weeks in year
   	IW		--	No of weeks in year from ISO standard
   	HH		--	Hours
   	MI		--	Minutes
   	SS		--	Seconds
   	FF		--	Fractional seconds
   	AM or PM	--	Displays AM or PM depending upon time of day
   	A.M or P.M	--	Displays A.M or P.M depending upon time of day
   	AD or BC	--	Displays AD or BC depending upon the date
   	A.D or B.C	--	Displays AD or BC depending upon the date
   	FM		--	Prefix to month or day, suppresses padding of month or day
   	TH		--	Suffix to a number
   	SP		--	suffix to a number to be spelled out
   	SPTH 		--	Suffix combination of TH and SP to be both spelled out
   	THSP		--	same as SPTH
   

   Ex:
   SQL> select to_char(sysdate,'dd month yyyy hh:mi:ss am dy') from dual;

   TO_CHAR(SYSDATE,'DD MONTH YYYYHH:MI
   ------------------------------------
   24 december  2006 02:03:23 pm sun	
   

   SQL> select to_char(sysdate,'dd month year') from dual;

   TO_CHAR(SYSDATE,'DDMONTHYEAR')
   -------------------------------
   24 december  two thousand six
   

   SQL> select to_char(sysdate,'dd fmmonth year') from dual;

   TO_CHAR(SYSDATE,'DD FMMONTH YEAR')
   ----------------------------------
   24 december two thousand six
   

   SQL> select to_char(sysdate,'ddth DDTH') from dual;

   TO_CHAR(S
   ------------
   24th 24TH
   

   SQL> select to_char(sysdate,'ddspth DDSPTH') from dual;

   TO_CHAR(SYSDATE,'DDSPTHDDSPTH
   -----------------------------
   twenty-fourth TWENTY-FOURTH
   

   SQL> select to_char(sysdate,'ddsp Ddsp DDSP ') from dual;

   TO_CHAR(SYSDATE,'DDSPDDSPDDSP')
   ------------------------------------
   twenty-four Twenty-Four TWENTY-FOUR
   

9. TO_DATE
   This will be used to convert the string into data format.

   Syntax:
   to_date (date)

   Ex:
   SQL> select to_char(to_date('24/dec/2006','dd/mon/yyyy'), 'dd * month * day') from dual;

   TO_CHAR(TO_DATE('24/DEC/20
   --------------------------
   24 * december  * Sunday
   

   -- If you are not using to_char oracle will display output in default date format.
10. ADD_MONTHS
    This will add the specified months to the given date.

    Syntax:
    add_months (date, no_of_months)

    Ex:
    SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), 5) from dual;

    ADD_MONTHS
    -----------
    11-JUN-90
    

    SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), -5) from dual;

    ADD_MONTH
    ----------
    11-AUG-89           
    

    • If no_of_months is zero then it will display the same date.
    • If no_of_months is null then it will display nothing.
11. MONTHS_BETWEEN
    This will give difference of months between two dates.

    Syntax:
    months_between (date1, date2)

    Ex:
    SQL> select months_between(to_date('11-aug-1990','dd-mon-yyyy'), to_date('11-jan- 1990','dd-mon-yyyy')) from dual;

    MONTHS_BETWEEN(TO_DATE('11-AUG-1990','DD-MON-YYYY'),TO_DATE('11-JAN-1990','DD-MON-YYYY'))
    ---------------------------------------------------------------------------------------
                             7
    

    SQL> select months_between(to_date('11-jan-1990','dd-mon-yyyy'), to_date('11-aug- 1990','dd-mon-yyyy')) from dual;

    MONTHS_BETWEEN(TO_DATE('11-JAN-1990','DD-MON-YYYY'),TO_DATE('11-AUG-1990','DD-MON-YYYY'))
    ----------------------------------------------------------------------------------------
                              -7
    

12. NEXT_DAY
    This will produce next day of the given day from the specified date.

    Syntax:
    next_day (date, day)

    Ex:
    SQL> select next_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;

    NEXT_DAY(
    ----------
    31-DEC-06
    

    -- If the day parameter is null then it will display nothing.
13. LAST_DAY
    This will produce last day of the given date.

    Syntax:
    last_day (date)

    Ex:
    SQL> select last_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;

    LAST_DAY(
    ----------
    31-DEC-06
    

14. EXTRACT
    This is used to extract a portion of the date value.

    Syntax:
    extract ((year | month | day | hour | minute | second), date)

    Ex:
    SQL> select extract(year from sysdate) from dual;

    		 
    EXTRACT(YEARFROMSYSDATE)
    ------------------------
              2006
    

    -- You can extract only one value at a time.
15. GREATEST
    This will give the greatest date.

    Syntax:
    greatest (date1, date2, date3 ... daten)

    Ex:
    SQL> select greatest(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon- yy'),to_date('11-apr-90','dd-mon-yy')) from dual;

      GREATEST(
      -----------
       11-APR-90
    

16. LEAST
    This will give the least date.

    Syntax:
    least (date1, date2, date3 ... daten)

    Ex:
    SQL> select least(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon- yy'),to_date('11-apr-90','dd-mon-yy')) from dual;

      LEAST(
      -----------
       11-JAN-90
    

17. ROUND
    Round will rounds the date to which it was equal to or greater than the given date.

    Syntax:
    round (date, (day | month | year))

    If the second parameter was year then round will checks the month of the given date in the following ranges.

    	JAN	--	JUN	
    	JUL --	DEC
    	

    If the month falls between JAN and JUN then it returns the first day of the current year. If the month falls between JUL and DEC then it returns the first day of the next year.

    If the second parameter was month then round will checks the day of the given date in the following ranges.

    	1	--	15	
    	16 	--	31
    	

    If the day falls between 1 and 15 then it returns the first day of the current month. If the day falls between 16 and 31 then it returns the first day of the next month.

    If the second parameter was day then round will checks the week day of the given date in the following ranges.

    	SUN	--	WED
    	THU --	SUN
    	

    If the week day falls between SUN and WED then it returns the previous sunday.
    If the weekday falls between THU and SUN then it returns the next sunday.
    • If the second parameter was null then it returns nothing.
    • If the you are not specifying the second parameter then round will resets the time to the begining of the current day in case of user specified date.
    • If the you are not specifying the second parameter then round will resets the time to the begining of the next day in case of sysdate.
    Ex:
    SQL> select round(to_date('24-dec-04','dd-mon-yy'),'year'), round(to_date('11-mar- 06','dd-mon-yy'),'year') from dual;

    ROUND(TO_ 	ROUND(TO_
    ------------   ---------------
    01-JAN-05   	01-JAN-06
    

    SQL> select round(to_date('11-jan-04','dd-mon-yy'),'month'), round(to_date('18-jan- 04','dd-mon-yy'),'month') from dual;

    ROUND(TO_ 	ROUND(TO_
    -------------  ---------------
    01-JAN-04   	 01-FEB-04
    

    SQL> select round(to_date('26-dec-06','dd-mon-yy'),'day'), round(to_date('29-dec- 06','dd-mon-yy'),'day') from dual;

       
    ROUND(TO_	 ROUND(TO_
    --------------  --------------
    24-DEC-06   	  31-DEC-06
    

    SQL> select to_char(round(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss am') from dual;

    TO_CHAR(ROUND(TO_DATE('
    ------------------------
    24 dec 2006 12:00:00 am
    

18. TRUNC
    Trunc will chops off the date to which it was equal to or less than the given date.

    Syntax:
    trunc (date, (day | month | year))

    • If the second parameter was year then it always returns the first day of the current year.
    • If the second parameter was month then it always returns the first day of the current month.
    • If the second parameter was day then it always returns the previous sunday.
    • If the second parameter was null then it returns nothing.
    • If the you are not specifying the second parameter then trunk will resets the time to the begining of the current day.

    Ex:
    SQL> select trunc(to_date('24-dec-04','dd-mon-yy'),'year'), trunc(to_date('11-mar- 06','dd-mon-yy'),'year') from dual;

    TRUNC(TO_	 TRUNC(TO_
    -------------  ------------
    01-JAN-04   	 01-JAN-06
    

    SQL> select trunc(to_date('11-jan-04','dd-mon-yy'),'month'), trunc(to_date('18-jan- 04','dd-mon-yy'),'month') from dual;

    TRUNC(TO_ 	TRUNC(TO_
    -------------  ------------
    01-JAN-04   	 01-JAN-04
    

    SQL> select trunc(to_date('26-dec-06','dd-mon-yy'),'day'), trunc(to_date('29-dec-06','dd- mon-yy'),'day') from dual;

    TRUNC(TO_ 	TRUNC(TO_
    -------------  --------
    24-DEC-06 	24-DEC-06
    

    SQL> select to_char(trunc(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss am') from dual;

    TO_CHAR(TRUNC(TO_DATE('
    ------------------------
    24 dec 2006 12:00:00 am
    

19. NEW_TIME
    This will give the desired timezone's date and time.

    Syntax:
    new_time (date, current_timezone, desired_timezone)

    Available timezones are as follows.              TIMEZONES

    		AST/ADT	--	Atlantic standard/day light time
    		BST/BDT	--	Bering standard/day light time
    		CST/CDT	--	Central standard/day light time
    		EST/EDT	--	Eastern standard/day light time
    		GMT    	--	Greenwich mean time
    		HST/HDT	--	Alaska-Hawaii standard/day light time
    		MST/MDT	--	Mountain standard/day light time
    		NST	 --	Newfoundland standard time
    		PST/PDT	--	Pacific standard/day light time
    		YST/YDT	--	Yukon standard/day light time
    

    Ex:
    SQL> select to_char(new_time(sysdate,'gmt','yst'),'dd mon yyyy hh:mi:ss am') from dual;

    TO_CHAR(NEW_TIME(SYSDAT
    ------------------------
    24 dec 2006 02:51:20 pm
    

    SQL> select to_char(new_time(sysdate,'gmt','est'),'dd mon yyyy hh:mi:ss am') from dual;

    TO_CHAR(NEW_TIME(SYSDAT
    -----------------------
    24 dec 2006 06:51:26 pm
    

20. COALESCE
    This will give the first non-null date.

    Syntax:
    coalesce (date1, date2, date3 ... daten)

    Ex:
    SQL> select coalesce('12-jan-90','13-jan-99'), coalesce(null,'12-jan-90','23-mar-98',null) from dual;

    COALESCE(    COALESCE(
    ----------  ------------
    12-jan-90     12-jan-90
    

MISCELLANEOUS  FUNCTIONS

• Uid
• User
• Vsize
• Rank
• Dense_rank

1. UID
   This will returns the integer value corresponding to the user currently logged in.

   Ex:
   SQL> select uid from dual;

          UID
         -----
          319
   

2. USER
   This will returns the login's user name.

   Ex:
   SQL> select user from dual;

   USER
   ------
   SAKETH
   

3. VSIZE
   This will returns the number of bytes in the expression.

   Ex:
   SQL> select vsize(123), vsize('computer'), vsize('12-jan-90') from dual;

   VSIZE(123)   VSIZE('COMPUTER')   VSIZE('12-JAN-90')
   ----------   -----------------  ------------------
        3            	8                9
   

4. RANK
   This will give the non-sequential ranking.

   Ex:
   SQL> select rownum,sal from (select sal from emp order by sal desc);

          ROWNUM    SAL
       ---------- ----------
            1       5000
            2       3000
            3       3000
            4       2975
            5       2850
            6       2450
            7       1600
            8       1500
            9       1300
           10       1250
           11       1250
           12       1100
           13       1000
           14        950
           15        800
   

   SQL> select rank(2975) within group(order by sal desc) from emp;

   	 
   RANK(2975)WITHINGROUP(ORDERBYSALDESC)
   ------------------------------------
                 4
   

5. DENSE_RANK
   This will give the sequential ranking.

   Ex:
   SQL> select dense_rank(2975) within group(order by sal desc) from emp;

   DENSE_RANK(2975)WITHINGROUP(ORDERBYSALDESC)
   ------------------------------------------
                     3
   

CONVERSION FUNCTIONS

• Bin_to_num
• Chartorowid
• Rowidtochar
• To_number
• To_char
• To_date

1. BIN_TO_NUM
   This will convert the binary value to its numerical equivalent.

   Syntax:
   bin_to_num( binary_bits)

   Ex:
   SQL> select bin_to_num(1,1,0) from dual;

   BIN_TO_NUM(1,1,0)
   -----------------
          6
   

   • If all the bits are zero then it produces zero.
   • If all the bits are null then it produces an error.
2. CHARTOROWID
   This will convert a character string to act like an internal oracle row identifier or rowid.
3. ROWIDTOCHAR
   This will convert an internal oracle row identifier or rowid to character string.
4. TO_NUMBER
   This will convert a char or varchar to number.
5. TO_CHAR
   This will convert a number or date to character string.
6. TO_DATE
   This will convert a number, char or varchar to a date.

GROUP FUNCTIONS

• Sum
• Avg
• Max
• Min
• Count

1. SUM
   This will give the sum of the values of the specified column.
   Syntax:
   sum (column)
   Ex:
   
   SQL> select sum(sal) from emp;

     SUM(SAL)
      ----------
        38600
   

2. AVG
   This will give the average of the values of the specified column.
   Syntax:
   avg (column)
   Ex:
   
   SQL> select avg(sal) from emp;

      AVG(SAL)
      ---------------
      2757.14286
   

3. MAX
   This will give the maximum of the values of the specified column.
   Syntax:
   max (column)
   Ex:
   
   SQL> select max(sal) from emp;

       MAX(SAL)
      ----------
        5000
   

4. MIN
   This will give the minimum of the values of the specified column.
   Syntax:
   min (column)
   Ex:
   
   SQL> select min(sal) from emp;

      MIN(SAL)
      ----------
        500
   

5. COUNT
   This will give the count of the values of the specified column.
   Syntax:
   count (column)
   Ex:
   
   SQL> select count(sal),count(*) from emp;

   COUNT(SAL)   COUNT(*)
   --------------    ------------
           14         	      14
   

CONSTRAINTS

• Domain integrity constraints
  • Not null
  • Check
• Entity integrity constraints
  • Unique
  • Primary key
• Referential integrity constraints
  • Foreign key

• Column level -- along with the column definition
• Table level -- after the table definition
• Alter level -- using alter command

NOT NULL

CHECK

COLUMN LEVEL

TABLE LEVEL

ALTER LEVEL

UNIQUE

COLUMN LEVEL

TABLE LEVEL

ALTER LEVEL

PRIMARY KEY

COLUMN LEVEL

TABLE LEVEL

ALTER LEVEL

FOREIGN KEY

TABLE LEVEL

ALTER LEVEL

USING ON DELTE CASCADE

TABLE LEVEL

ALTER LEVEL

COMPOSITE KEYS

UNIQUE (TABLE LEVEL)

UNIQUE (ALTER LEVEL)

PRIMARY KEY (TABLE LEVEL)

PRIMARY KEY (ALTER LEVEL)

FOREIGN KEY (TABLE LEVEL)

FOREIGN KEY (ALTER LEVEL)

DEFERRABLE CONSTRAINTS

• Deferred initially immediate
• Deferred initially deferred

OPERATIONS WITH CONSTRAINTS

• Enable
• Disable
• Enforce
• Drop

ENABLE

DISABLE

ENFORCE

DROP

CASE AND DEFAULT

CASE

       SAL 	CASE
      ----- --------
       500 	low
      2500 	medium
      2000 	medium
      3500 	medium
      3000 	medium
      5000 	high
      4000 	medium
      5000 	high
      1800 	medium
      1200 	medium
      2000 	medium
      2700 	medium
      2200 	medium
      3200 	medium

DEFAULT

        NO   NAME
      ------ ---------
         1 	a
        11 	b

        NO   NAME
      ------ ---------
         1 	a
        11 	b

ABSTRACT DATA TYPES

CREATING ADT

CREATING TABLE BASED ON ADT

INSERTING DATA INTO ADT TABLES

SELECTING DATA FROM ADT TABLES

        NO     NAME ADDRESS(HNO, CITY)
        ---    ---- --------------------
         1        a     ADDR(111, 'hyd')
         2        b     ADDR(222, 'bang')
         3        c     ADDR(333, 'delhi')

        NO    NAME   ADDRESS.HNO    ADDRESS.CITY
        --  ----     ---------   ------------
         1   a        111 		hyd
         2   b        222 		bang
         3   c        333 		delhi

UPDATE WITH ADT TABLES

        NO NAME     ADDRESS.HNO     ADDRESS.CITY
        --- ------    -------   ----------------
         1 	a          111 		hyd
         2 	b          222 		bang
         3 	c          333 		bombay

DELETE WITH ADT TABLES

        NO   NAME  ADDRESS.HNO ADDRESS.CITY
        --   ---- ------------ ----------------
         2 	b          222 		bang
         3 	c          333 		bombay

DROPPING ADT

OBJECT VIEWS AND METHODS

OBJECT VIEWS

1. Assume that the table student has already been created with the following columns
   SQL> create table student(no number(2),name varchar(10),hno number(3),city varchar(10));
2. Create the following types
   SQL> create type addr as object(hno number(2),city varchar(10));/
   SQL> create type stud as object(name varchar(10),address addr);/
3. Relate the objects to the student table by creating the object view
   SQL> create view student_ov(no,stud_info) as select no,stud(name,addr(hno,city)) from student;
4. Now you can insert data into student table in two ways
   1. By regular insert
      SQL> Insert into student values(1,'sudha',111,'hyd');
   2. By using object view
      SQL> Insert into student_ov values(1,stud('sudha',addr(111,'hyd')));

METHODS

1. Defining methods in types
   SQL> Create type stud as object(name varchar(10),marks number(3), Member function makrs_f(marks in number) return number, Pragma restrict_references(marks_f,wnds,rnds,wnps,fnps));/
2. Defining type body
   SQL> Create type body stud as Member function marks_f(marks in number) return number is Begin Return (marks+100); End marks_f; End;/
3. Create a table using stud type
   SQL> Create table student(no number(2),info stud);
4. Insert some data into student table
   SQL> Insert into student values(1,stud('sudha',100));
5. Using method in select
   SQL> Select s.info.marks_f(s.info.marks) from student s;

VARRAYS AND NESTED TABLES

VARRAYS

1. We can create varrays using oracle types as well as user defined types.
   1. Varray using pre-defined types
      SQL> Create type va as varray(5) of varchar(10);/
   2. Varrays using user defined types
      SQL> Create type addr as object(hno number(3),city varchar(10));/
      SQL> Create type va as varray(5) of addr;/
2. Using varray in table
   SQL> Create table student(no number(2),name varchar(10),address va);
3. Inserting values into varray table
   SQL> Insert into student values(1,'sudha',va(addr(111,'hyd')));
   SQL> Insert into student values(2,'jagan',va(addr(111,'hyd'),addr(222,'bang')));
4. Selecting data from varray table
   SQL> Select * from student;
   -- This will display varray column data along with varray and adt;
   SQL> Select no,name, s.* from student s1, table(s1.address) s; -- This will display in general format
5. Instead of s.* you can specify the columns in varray
   SQL> Select no,name, s.hno,s.city from student s1,table(s1.address) s; -- Update and delete not possible in varrays.
   -- Here we used table function which will take the varray column as input for producing output excluding varray and types.

NESTED TABLES

1. We can create nested tables using oracle types and user defined types which has no limit
   1. Nested tables using pre-defined types
      SQL> Create type nt as table of varchar(10);/
   2. Nested tables using user defined types
      SQL> Create type addr as object(hno number(3),city varchar(10));/
      SQL> Create type nt as table of addr;/
2. Using nested table in table
   SQL> Create table student(no number(2),name varchar(10),address nt) nested table address store as student_temp;
3. Inserting values into table which has nested table
   SQL> Insert into student values (1,'sudha',nt(addr(111,'hyd')));
   SQL> Insert into student values (2,'jagan',nt(addr(111,'hyd'),addr(222,'bang')));
4. Selecting data from table which has nested table
   SQL> Select * from student;
   -- This will display nested table column data along with nested table and adt;
   SQL> Select no,name, s.* from student s1, table(s1.address) s;
   -- This will display in general format
5. Instead of s.* you can specify the columns in nested table
   SQL> Select no,name, s.hno,s.city from student s1,table(s1.address) s;
6. Inserting nested table data to the existing row
   SQL> Insert into table(select address from student where no=1) values(addr(555,'chennai'));
7. Update in nested tables
   SQL> Update table(select address from student where no=2) s set s.city='bombay' where s.hno = 222;
8. Delete in nested table
   SQL> Delete table(select address from student where no=3) s where s.hno=333;

• ALL_COLL_TYPES
• ALL_TYPES
• DBA_COLL_TYPES
• DBA_TYPES
• USER_COLL_TYPES
• USER_TYPES

FLASHBACK QUERY

• Time base flashback
• SCN based flashback (SCN stands for System Change Number)

1. Using time based flashback
   1. SQL> Select *from student;
      -- This will display all the rows
   2. SQL> Delete student;
   3. SQL> Commit; -- this will commit the work.
   4. SQL> Select *from student;
      -- Here it will display nothing
   5. Then execute the following procedures
      SQL> Exec dbms_flashback.enable_at_time(sysdate-2/1440)
   6. SQL> Select *from student;
      -- Here it will display the lost data
      -- The lost data will come but the current system time was used
   7. SQL> Exec dbms_flashback.disable
      -- Here we have to disable the flashback to enable it again
2. Using SCN based flashback
   1. Declare a variable to store SCN
      SQL> Variable s number
   2. Get the SCN
      SQL> Exec :s := exec dbms_flashback.get_system_change_number
   3. To see the SCN
      SQL> Print s
   4. Then execute the following procedures
      SQL> Exec dbms_flashback.enable_at_system_change_number(:s)
      SQL> Exec dbms_flashback.disable

EXTERNAL TABLES

• You can user external table feature to access external files as if they are tables inside the database.
• When you create an external table, you define its structure and location with in oracle.
• When you query the table, oracle reads the external table and returns the results just as if the data had been stored with in the database.

ACCESSING EXTERNAL TABLE DATA

• To access external files from within oracle, you must first use the create directory command to define a directory object pointing to the external file location
• who will access the external files must have the read and write privilege on the directory.

CREATING DIRECTORY AND OS LEVEL FILE

CREATING EXTERNAL TABLE

SELECTING DATA FROM EXTERNAL TABLE

LIMITATIONS ON EXTERNAL TABLES

1. You can not perform insert, update, and delete operations
2. Indexing not possible
3. Constraints not possible

BENEFITS OF EXTERNAL TABLES

1. Queries of external tables complete very quickly even though a full table scan id required with each access
2. You can join external tables to each other or to standard tables

REF DEREF VALUE

REF

• The ref function allows referencing of existing row objects.
• Each of the row objects has an object id value assigned to it.
• The object id assigned can be seen by using ref function.

DEREF

• The deref function performs opposite action.
• It takes a reference value of object id and returns the value of the row objects.

VALUE

• Even though the primary table is object table, still it displays the rows in general format.
• To display the entire structure of the object, this will be used.

1. create vendot_adt type
   SQL> Create type vendor_adt as object (vendor_code number(2), vendor_name varchar(2), vendor_address varchar(10));/
2. create object tables vendors and vendors1
   SQL> Create table vendors of vendor_adt;
   SQL> Create table vendors1 of vendor_adt;
3. insert the data into object tables
   SQL> insert into vendors values(1, 'a', 'hyd');
   SQL> insert into vendors values(2, 'b', 'bang');
   SQL> insert into vendors1 values(3, 'c', 'delhi');
   SQL> insert into vendors1 values(4, 'd', 'chennai');
4. create another table orders which holds the vendor_adt type also.
   SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt); Or
   SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt with rowid);
5. insert the data into orders table
   The vendor_info column in the following syntaxes will store object id of any table which is referenced by vendor_adt object ( both vendors and vendors1).
   SQL> insert into orders values(11,(select ref(v) from vendors v where vendor_code = 1));
   SQL> insert into orders values(12,(select ref(v) from vendors v where vendor_code = 2));
   SQL> insert into orders values(13,(select ref(v1) from vendors1 v1 where vendor_code = 1));
   SQL> insert into orders values(14,(select ref(v1) from vendors1 v1 where vendor_code = 1));
6. To see the object ids of vendor table
   SQL> Select ref(V) from vendors v;
7. If you see the vendor_info of orders it will show only the object ids not the values, to see the values
   SQL> Select deref(o.vendor_info) from orders o;
8. Even though the vendors table is object table it will not show the adt along with data, to see the data along with the adt
   SQL>Select * from vendors;
   This will give the data without adt.
   SQL>Select value(v) from vendors v;
   This will give the columns data along wih the type.

REF CONSTRAINTS

• Ref can also acts as constraint.
• Even though vendors1 also holding vendor_adt, the orders table will store the object ids of vendors only because it is constrained to that table only.
• The vendor_info column in the following syntaxes will store object ids of vendors only.

OBJECT VIEWS WITH REFERENCES

• To implement the objects and the ref constraints to the existing tables, what we can do? Simply drop the both tables and recreate with objects and ref constrains.
• But you can achieve this with out dropping the tables and without losing the data by creating object views with references.

• Create the following tables
  SQL> Create table student1(no number(2) primary key,name varchar(2),marks number(3));
  SQL> Create table student2(no number(2) primary key,hno number(3),city varchar(10),id number(2),foreign Key(id) references student1(no));
• Insert the records into both tables
  SQL> insert into student1(1,'a',100);
  SQL> insert into student1(2,'b',200);
  SQL> insert into student2(11,111,'hyd',1);
  SQL> insert into student2(12,222,'bang',2);
  SQL> insert into student2(13,333,'bombay',1);
• Create the type
  SQL> create or replace type stud as object(no number(2),name varchar(2),marks number(3));/
• Generating OIDs
  SQL> Create or replace view student1_ov of stud with object identifier(or id) (no) as Select * from Student1;
• Generating references
  SQL> Create or replace view student2_ov as select no,hno,city,make_ref(student1_ov,id) id from Student2;
• Query the following
  SQL> select *from student1_ov;
  SQL> select ref(s) from student1_ov s;
  SQL> select values(s) from student1_ov;
  SQL> select *from student2_ov;
  SQL> select deref(s.id) from student2_ov s;

PARTITIONS

• A single logical table can be split into a number of physically separate pieces based on ranges of key values. Each of the parts of the table is called a partition.
• A non-partitioned table can not be partitioned later.

TYPES

• Range partitions
• List partitions
• Hash partitions
• Sub partitions

ADVANTAGES

• Reducing downtime for scheduled maintenance, which allows maintenance operations to be carried out on selected partitions while other partitions are available to users.
• Reducing downtime due to data failure, failure of a particular partition will no way affect other partitions.
• Partition independence allows for concurrent use of the various partitions for various purposes.

ADVANTAGES OF PARTITIONS BY STORING THEM IN DIFFERENT TABLESPACES

• Reduces the possibility of data corruption in multiple partitions.
• Back up and recovery of each partition can be done independently.

DISADVANTAGES

• Partitioned tables cannot contain any columns with long or long raw datatypes, LOB types or object types.

RANGE PARTITIONS

1. Creating range partitioned table
   SQL> Create table student(no number(2),name varchar(2)) partition by range(no) (partition p1 values less than(10), partition p2 values less than(20), partition p3 values less than(30),partition p4 values less than(maxvalue));
   ** if you are using maxvalue for the last partition, you can not add a partition.
2. Inserting records into range partitioned table
   SQL> Insert into student values(1,'a'); -- this will go to p1
   SQL> Insert into student values(11,'b'); -- this will go to p2
   SQL> Insert into student values(21,'c'); -- this will go to p3
   SQL> Insert into student values(31,'d'); -- this will go to p4
3. Retrieving records from range partitioned table
   SQL> Select *from student;
   SQL> Select *from student partition(p1);
4. Possible operations with range partitions
   • Add
   • Drop
   • Truncate
   • Rename
   • Split
   • Move
   • Exchange
5. Adding a partition
   SQL> Alter table student add partition p5 values less than(40);
6. Dropping a partition
   SQL> Alter table student drop partition p4;
7. Renaming a partition
   SQL> Alter table student rename partition p3 to p6;
8. Truncate a partition
   SQL> Alter table student truncate partition p6;
9. Splitting a partition
   SQL> Alter table student split partition p2 at(15) into (partition p21,partition p22);
10. Exchanging a partition
    SQL> Alter table student exchange partition p1 with table student2;
11. Moving a partition
    SQL> Alter table student move partition p21 tablespace saketh_ts;

LIST PARTITIONS

1. Creating list partitioned table
   SQL> Create table student(no number(2),name varchar(2)) partition by list(no) (partition p1 values(1,2,3,4,5), partition p2 values(6,7,8,9,10),partition p3 values(11,12,13,14,15), partition p4 values(16,17,18,19,20));
2. Inserting records into list partitioned table
   SQL> Insert into student values(1,'a'); -- this will go to p1
   SQL> Insert into student values(6,'b'); -- this will go to p2
   SQL> Insert into student values(11,'c'); -- this will go to p3
   SQL> Insert into student values(16,'d'); -- this will go to p4
3. Retrieving records from list partitioned table
   SQL> Select *from student;
   SQL> Select *from student partition(p1);
4. Possible operations with list partitions
   • Add
   • Drop
   • Truncate
   • Rename
   • Move
   • Exchange
5. Adding a partition
   SQL> Alter table student add partition p5 values(21,22,23,24,25);
6. Dropping a partition
   SQL> Alter table student drop partition p4;
7. Renaming a partition
   SQL> Alter table student rename partition p3 to p6;
8. Truncate a partition
   SQL> Alter table student truncate partition p6;
9. Exchanging a partition
   SQL> Alter table student exchange partition p1 with table student2;
10. Moving a partition
    SQL> Alter table student move partition p2 tablespace saketh_ts;

HASH PARTITIONS

1. Creating hash partitioned table
   SQL> Create table student(no number(2),name varchar(2)) partition by hash(no) partitions 5;
   Here oracle automatically gives partition names like
   SYS_P1
   SYS_P2
   SYS_P3
   SYS_P4
   SYS_P5
2. Inserting records into hash partitioned table it will insert the records based on hash function calculated by taking the partition key
   SQL> Insert into student values(1,'a');
   SQL> Insert into student values(6,'b');
   SQL> Insert into student values(11,'c');
   SQL> Insert into student values(16,'d');
3. Retrieving records from hash partitioned table
   SQL> Select *from student;
   SQL> Select *from student partition(sys_p1);
4. Possible operations with hash partitions
   • Add
   • Truncate
   • Rename
   • Move
   • Exchange
5. Adding a partition
   SQL> Alter table student add partition p6 ;
6. Renaming a partition
   SQL> Alter table student rename partition p6 to p7;
7. Truncate a partition
   SQL> Alter table student truncate partition p7;
8. Exchanging a partition
   SQL> Alter table student exchange partition sys_p1 with table student2;
9. Moving a partition
   SQL> Alter table student move partition sys_p2 tablespace saketh_ts;

SUB-PARTITIONS WITH RANGE AND HASH

1. Creating subpartitioned table
   SQL> Create table student(no number(2),name varchar(2),marks number(3)) Partition by range(no) subpartition by hash(name) subpartitions 3 (Partition p1 values less than(10),partition p2 values less than(20));

   This will create two partitions p1 and p2 with three subpartitions for each partition

   		P1 -   SYS_SUBP1
   			SYS_SUBP2
   			SYS_SUBP3
   		P2 -   SYS_SUBP4
   			SYS_SUBP5
   			SYS_SUBP6
   

   ** if you are using maxvalue for the last partition, you can not add a partition.
2. Inserting records into subpartitioned table
   SQL> Insert into student values(1,'a'); -- this will go to p1
   SQL> Insert into student values(11,'b'); -- this will go to p2
3. Retrieving records from subpartitioned table
   SQL> Select *from student;
   SQL> Select *from student partition(p1);
   SQL> Select *from student subpartition(sys_subp1);
4. Possible operations with subpartitions
   • Add
   • Drop
   • Truncate
   • Rename
   • Split
5. Adding a partition
   SQL> Alter table student add partition p3 values less than(30);
6. Dropping a partition
   SQL> Alter table student drop partition p3;
7. Renaming a partition
   SQL> Alter table student rename partition p2 to p3;
8. Truncate a partition
   SQL> Alter table student truncate partition p1;
9. Splitting a partition
   SQL> Alter table student split partition p3 at(15) into (partition p31,partition p32);

DATA MODEL

• ALL_IND_PARTITIONS
• ALL_IND_SUBPARTITIONS
• ALL_TAB_PARTITIONS
• ALL_TAB_SUBPARTITIONS
• DBA_IND_PARTITIONS
• DBA_IND_SUBPARTITIONS
• DBA_TAB_PARTITIONS
• DBA_TAB_SUBPARTITIONS
• USER_IND_PARTITIONS
• USER_IND_SUBPARTITIONS
• USER_TAB_PARTITIONS
• USER_TAB_SUBPARTITIONS

GROUP BY AND HAVING

GROUP BY

• Using group by, we can create groups of related information.
• Columns used in select must be used with group by, otherwise it was not a group by expression.

    DEPTNO   SUM(SAL)
---------- ----------
        10       8750
        20      10875
        30       9400

     DEPTNO  JOB         SUM(SAL)
---------- ---------   ----------
        10   CLERK          1300
        10   MANAGER        2450
        10   PRESIDENT      5000
        20   ANALYST        6000
        20   CLERK          1900
        20   MANAGER        2975
        30   CLERK          950
        30   MANAGER        2850
        30   SALESMAN       5600

HAVING

      DEPTNO   JOB              TSAL
   ----------  ---------      ----------
        10    PRESIDENT         5000
        20    ANALYST           6000
        30    SALESMAN          5600

    DEPTNO    JOB          TSAL
 ----------  ---------    ----------
     20       ANALYST       6000
     10       PRESIDENT     5000
     30       SALESMAN      5600

ORDER OF EXECUTION

• Group the rows together based on group by clause.
• Calculate the group functions for each group.
• Choose and eliminate the groups based on the having clause.
• Order the groups based on the specified column.

ROLLUP GROUPING CUBE

USING ROLLUP

This will give the salaries in each department in each job category along wih the total salary fot individual departments and the total salary of all the departments.

     DEPTNO   JOB         SUM(SAL)
----------  ---------   ----------
        10    CLERK       1300
        10    MANAGER     2450
        10    PRESIDENT   5000
        10                8750
        20    ANALYST     6000
        20    CLERK       1900
        20    MANAGER     2975
        20                10875
        30    CLERK        950
        30    MANAGER     2850
        30    SALESMAN    5600
        30                9400
                          29025

USING GROUPING

DECODE(GROUPING(DEPTNO),1,'ALLDEPTS',DEP DECODE(GR   SUM(SAL)
-------------------------- -----------------------   --------------
10                                     CLERK           	1300
10                                     MANAGER         	2450
10                                     PRESIDENT       	5000
10                                     All jobs         8750
20                                     ANALYST         	6000
20                                     CLERK           	1900
20                                     MANAGER         	2975
20                                     All jobs         10875
30                                     CLERK        	  950
30                                     MANAGER         	2850
30                                     SALESMAN        	5600
30                                     All jobs         9400
All Depts                              All jobs         29025

• Grouping will return 1 if the column which is specified in the grouping function has been used in rollup.
• Grouping will be used in association with decode.

USING CUBE

DECODE(GROUPING(DEPTNO),1,'ALLDEPTS',DEP DECODE(GR   SUM(SAL)
------------------------- ------------------------   ------------
10                                 CLERK               1300
10                                 MANAGER         	   2450
10                                 PRESIDENT       	   5000
10                                 All Jobs        	   8750
20                                 ANALYST         	   6000
20                                 CLERK           	   1900
20                                 MANAGER         	   2975
20                                 All Jobs            10875
30                                 CLERK                950
30                                 MANAGER             2850
30                                 SALESMAN            5600
30                                 All Jobs            9400
All Depts                          ANALYST             6000
All Depts                          CLERK               4150
All Depts                          MANAGER             8275
All Depts                          PRESIDENT           5000
All Depts                          SALESMAN        	   5600
All Depts                          All Jobs       	   29025

SET OPERATORS

TYPES

• Union
• Union all
• Intersect
• Minus

UNION

UNION ALL

INTERSECT

MINUS

VIEWS

• A view is a database object that is a logical representation of a table. It is delivered from a table but has no storage of its own and often may be used in the same manner as a table.
• A view takes the output of the query and treats it as a table, therefore a view can be thought of as a stored query or a virtual table.

TYPES

• Simple view
• Complex view

WHY VIEWS?

• Provides additional level of security by restricting access to a predetermined set of rows and/or columns of a table.
• Hide the data complexity.
• Simplify commands for the user.

VIEWS WITHOUT DML

• Read only view
• View with group by
• View with aggregate functions
• View with rownum
• Partition view
• View with distinct

VIEWS WITH DML

• View with not null column
  -- insert with out not null column not possible
  -- update not null column to null is not possible
  -- delete possible
• View with out not null column which was in base table
  -- insert not possible
  -- update, delete possible
• View with expression
  -- insert , update not possible
  -- delete possible
• View with functions (except aggregate)
  -- insert, update not possible
  -- delete possible
• View was created but the underlying table was dropped then we will get the message like " view has errors ".
• View was created but the base table has been altered but still the view was with the initial definition, we have to replace the view to affect the changes.
• Complex view (view with more than one table)
  -- insert not possible
  -- update, delete possible (not always)

CREATING VIEW WITHOUT HAVING THE BASE TABLE

VIEW WITH CHECK OPTION CONSTRAINT

DROPPING VIEWS

SYNONYM AND SEQUENCE

SYNONYM

TYPES

• Private
• Public

• Private synonym is available to the particular user who creates.
• Public synonym is created by DBA which is available to all the users.

ADVANTAGES

• Hide the name and owner of the object.
• Provides location transparency for remote objects of a distributed database.

CREATE AND DROP

SEQUENCE

• A sequence is a database object, which can generate unique, sequential integer values.
• It can be used to automatically generate primary key or unique key values.
• A sequence can be either in an ascending or descending order.

By defalult the sequence starts with 1, increments by 1 with minvalue of 1 and with nocycle, nocache.

Cache option pre-alloocates a set of sequence numbers and retains them in memory for faster access.

USING SEQUENCE

• Initially currval is not defined and nextval is starting value.
• After that nextval and currval are always equal.

CREATING ALPHA-NUMERIC SEQUENCE

ALTERING SEQUENCE

• Set or eliminate minvalue or maxvalue.
• Change the increment value.
• Change the number of cached sequence numbers.

DROPPING SEQUENCE

JOINS

• The purpose of a join is to combine the data across tables.
• A join is actually performed by the where clause which combines the specified rows of tables.
• If a join involves in more than two tables then oracle joins first two tables based on the joins condition and then compares the result with the next table and so on.

TYPES

• Equi join
• Non-equi join
• Self join
• Natural join
• Cross join
• Outer join
• Left outer
• Right outer
• Full outer
• Inner join
• Using clause
• On clause

 
      DEPTNO   DNAME      LOC 
     ------ ---------- ---------- 
        10 	mkt        hyd 
        20 	fin        bang 
        30 	hr         bombay 

 
       EMPNO       ENAME      JOB       MGR     DEPTNO 
      ------    ---------- ---------- ---------- ---------- 
       111         saketh     analyst   444         10 
       222         sudha      clerk     333         20 
       333         jagan      manager   111         10 
       444         madhu      engineer  222         40 

EQUI JOIN

 
       EMPNO  ENAME      JOB     DNAME        LOC 
      ------  --------- ------- ---------- ---------- 
       	111   saketh    analyst    mkt        hyd 
       	333   jagan     manager    mkt        hyd 
       	222   sudha     clerk      fin        bang 

USING CLAUSE

 
        EMPNO   ENAME      JOB      DNAME      LOC 
       ------- ---------- -------- ---------- ---------- 
       	111 	saketh    analyst    mkt        hyd 
       	333 	jagan     manager    mkt        hyd 
       	222 	sudha     clerk      fin        bang 

ON CLAUSE

 
        EMPNO   ENAME      JOB      DNAME      LOC 
       ------  ---------- -------- ---------- -------
       	111 	saketh    analyst    mkt        hyd 
       	333 	jagan     manager    mkt        hyd 
       	222 	sudha     clerk      fin        bang 

NON-EQUI JOIN

 
      EMPNO   ENAME      JOB        DNAME      LOC 
     ------- ---------- ---------- ---------- ---------- 
       222    sudha     clerk      mkt        hyd 
       444    madhu     engineer   mkt        hyd 
       444    madhu     engineer   fin        bang 
       444    madhu     engineer   hr         bombay 

SELF JOIN

 
     EMPNO     ENAME        JOB      DEPTNO 
     ------   --------     -------  -------- 
       111 	jagan      analyst    10 
       222 	madhu      clerk      40 
       333 	sudha      manager    20 
       444 	saketh     engineer   10 

NATURAL JOIN

 
     EMPNO       ENAME      JOB       DNAME       LOC 
    ---------- ---------- ---------- ------    -------- 
       111 	saketh     analyst     mkt        hyd 
       333 	jagan      manager     mkt        hyd 
       222 	sudha      clerk       fin        bang 

CROSS JOIN

 
       EMPNO   ENAME     JOB        DNAME      LOC 
     -------   ------- ----------  -------    ------ 
       111     saketh   analyst      mkt        hyd 
       222     sudha    clerk        mkt        hyd 
       333     jagan    manager      mkt        hyd 
       444     madhu    engineer     mkt        hyd 
       111     saketh   analyst      fin        bang 
       222     sudha    clerk        fin        bang 
       333     jagan    manager      fin        bang 
       444     madhu    engineer     fin        bang 
       111     saketh   analyst      hr         bombay 
       222     sudha    clerk        hr         bombay 
       333     jagan    manager      hr         bombay 
       444     madhu    engineer     hr         bombay 

OUTER JOIN

LEFT OUTER JOIN

 
       EMPNO     ENAME    JOB       DNAME      LOC 
     --------   -------- --------   --------  ------ 
       111 	saketh    analyst    mkt        hyd 
       333 	jagan     manager    mkt        hyd 
       222 	sudha     clerk      fin        bang 
       444 	madhu     engineer 

RIGHT OUTER JOIN

 
       EMPNO    ENAME      JOB      DNAME      LOC 
      -------  --------  ---------- ---------- ---------- 
       111 	saketh     analyst   mkt        hyd 
       333 	jagan      manager   mkt        hyd 
       222 	sudha      clerk     fin        bang 
                                     hr         bombay 

FULL OUTER JOIN

 
       EMPNO   ENAME    JOB        DNAME      LOC 
       ------ -------  ---------- ---------- ---------- 
       333     jagan    manager    mkt        hyd 
       111     saketh   analyst    mkt        hyd 
       222     sudha    clerk      fin        bang 
       444     madhu    engineer 
                                    hr        bombay 

INNER JOIN

 
       EMPNO    ENAME   JOB        DNAME      LOC 
       ------  -------- --------  --------  -------- 
       111 	saketh  analyst      mkt       hyd 
       333 	jagan   manager      mkt       hyd 
       222 	sudha   clerk        fin       bang 

SUBQUERIES AND EXISTS

SUBQUERIES

• Nesting of queries, one within the other is termed as a subquery.
• A statement containing a subquery is called a parent query.
• Subqueries are used to retrieve data from tables that depend on the values in the table itself.

TYPES

• Single row subqueries
• Multi row subqueries
• Multiple subqueries
• Correlated subqueries

SINGLE ROW SUBQUERIES

 
      EMPNO    ENAME      JOB        MGR    HIREDATE    SAL   COMM     DEPTNO 
    ---------- ------   ---------  ------- ----------  ----- ------   -------- 
      7788 	SCOTT    ANALYST    7566   19-APR-87    3000             20 
      7839 	KING     PRESIDENT         17-NOV-81    5000             10 
      7902 	FORD     ANALYST    7566   03-DEC-81    3000             20 

MULTI ROW SUBQUERIES

• In multi row subquery, it will return more than one value.
• In such cases we should include operators like any, all, in or not in between the comparision operator and the subquery.

 
      EMPNO    ENAME    JOB      MGR    HIREDATE   SAL   COMM     DEPTNO 
      ------   -------  ------- ------ ---------- ------ ------  --------- 
      7566 	JONES   MANAGER   7839 02-APR-81   2975               20 
      7788 	SCOTT   ANALYST   7566 19-APR-87   3000               20 
      7839 	KING    PRESIDENT      17-NOV-81   5000               10 
      7902 	FORD    ANALYST   7566 03-DEC-81   3000               20 

    
     EMPNO      ENAME    JOB       MGR     HIREDATE     SAL    COMM  DEPTNO 
     ------    -------  --------- -----   ----------   ------  ----- ------- 
      7839 	KING     PRESIDENT         17-NOV-81    5000           10 

MULTIPLE SUBQUERIES

• There is no limit on the number of subqueries included in a where clause.
• It allows nesting of a query within a subquery.

 
     EMPNO      ENAME   JOB      MGR       HIREDATE  SAL   COMM     DEPTNO 
     ---------- ------ -------- ---------- --------- ----- -----    ------- 
     7788 	SCOTT   ANALYST  7566    19-APR-87   3000             20 
     7902 	FORD    ANALYST  7566    03-DEC-81   3000             20 

CORRELATED SUBQUERIES

 
      DEPTNO 
      -------- 
        20 
        30 

EXISTS

 
   DEPTNO         COUNT(*) 
   ---------    ---------- 
       20             5 
       30             6 

     no rows selected

The above query returns nothing because combination of deptno and ename never return more than one count.

 
       DEPTNO   ENAME 
     --------- ---------- 
        20 	ADAMS 
        20 	FORD 
        20 	JONES 
        20 	SCOTT 
        20 	SMITH 
        30 	ALLEN 
        30 	BLAKE 
        30 	JAMES 
        30	MARTIN 
        30 	TURNER 
        30 	WARD 

NOT EXISTS

 
      DEPTNO    ENAME 
    --------- ---------- 
       10 	CLARK 
       10 	KING 
       10 	MILLER 

WALKUP TREES AND INLINE VIEW

WALKUP TREES

 
  
ENAME||'==>'||PRIORENAM      LEVEL 
------------------------   -------- 
KING==>                       1 
JONES==>KING                  2 
SCOTT==>JONES                 3 
ADAMS==>SCOTT                 4 
FORD==>JONES                  3 
SMITH==>FORD                  4 
BLAKE==>KING                  2 
ALLEN==>BLAKE                 3 
WARD==>BLAKE                  3 
MARTIN==>BLAKE                3 
TURNER==>BLAKE                3 
JAMES==>BLAKE                 3 
CLARK==>KING                  2 
MILLER==>CLARK                3 

• In the above Start with clause specifies the root row of the table.
• Level pseudo column gives the 1 for root , 2 for child and so on.
• Connect by prior clause specifies the columns which has parent-child relationship.

INLINE VIEW OR TOP-N ANALYSIS

 
ENAME             SAL       RANK 
-------        ----------  ------- 
SMITH             800        1 
JAMES             950        2 
ADAMS            1100        3 
WARD             1250        4 
MARTIN           1250        5 
MILLER           1300        6 
TURNER           1500        7 
ALLEN            1600        8 
CLARK            2450        9 
BLAKE            2850        10 
JONES            2975        11 
SCOTT            3000        12 
FORD             3000        13 
KING             5000        14 

LOCKS

• Locks are the mechanisms used to prevent destructive interaction between users accessing same resource simultaneously.
• Locks provides high degree of data concurrency.

TYPES

• Row level locks
• Table level locks

ROW LEVEL LOCKS

• In the row level lock a row is locked exclusively so that other cannot modify the row until the transaction holding the lock is committed or rolled back.
• This can be done by using select..for update clause.

TABLE LEVEL LOCKS

• Share lock
• Share update lock
• Exclusive lock

SHARE LOCK

• A share lock locks the table allowing other users to only query but not insert, update or delete rows in a table.
• Multiple users can place share locks on the same resource at the same time.

SHARE UPDATE LOCK

• It locks rows that are to be updated in a table.
• It permits other users to concurrently query, insert , update or even lock other rows in the same table.
• It prevents the other users from updating the row that has been locked.

EXCLUSIVE LOCK

• Exclusive lock is the most restrictive of tables locks.
• When issued by any user, it allows the other user to only query.
• It is similar to share lock but only one user can place exclusive lock on a table at a time.

NOWAIT

• If one user locked the table without nowait then another user trying to lock the same table then he has to wait until the user who has initially locked the table issues a commit or rollback statement.
• This delay could be avoided by appending a nowait clause in the lock table command.

DEADLOCK

• A deadlock occurs when tow users have a lock each on separate object, and they want to acquire a lock on the each other's object.
• When this happens, the first user has to wait for the second user to release the lock, but the second user will not release it until the lock on the first user's object is freed.
• In such a case, oracle detects the deadlock automatically and solves the problem by aborting one of the two transactions.

INDEXES

• Index is typically a listing of keywords accompanied by the location of information on a subject.
• We can create indexes explicitly to speed up SQL statement execution on a table.
• The index points directly to the location of the rows containing the value.

WHY INDEXES?

TYPES

• Unique index
• Non-unique index
• Btree index
• Bitmap index
• Composite index
• Reverse key index
• Function-based index
• Descending index
• Domain index
• Object index
• Cluster index
• Text index
• Index organized table
• Partition index
• Local index
• Local prefixed
• Local non-prefixed
• Global index
• Global prefixed
• Global non-prefixed

UNIQUE INDEX

• Unique indexes guarantee that no two rows of a table have duplicate values in the columns that define the index.
• Unique index is automatically created when primary key or unique constraint is created.

NON-UNIQUE INDEX

BTREE INDEX or ASCENDING INDEX

1. The default type of index used in an oracle database is the btree index.
2. A btree index is designed to provide both rapid access to individual rows and quick access to groups of rows within a range.
3. The btree index does this by performing a succession of value comparisons.
4. Each comparison eliminates many of the rows.

BITMAP INDEX

COMPOSITE INDEX

• A composite index also called a concatenated index is an index created on multiple columns of a table.
• Columns in a composite index can appear in any order and need not be adjacent columns of the table.

REVERSE KEY INDEX

1. A reverse key index when compared to standard index, reverses each byte of the column being indexed while keeping the column order.
2. When the column is indexed in reverse mode then the column values will be stored in an index in different blocks as the starting value differs.
3. Such an arrangement can help avoid performance degradations in indexes where modifications to the index are concentrated on a small set of blocks.

FUNCTION BASED INDEX

DESCENDING INDEX

1. The order used by B-tree indexes has been ascending order.
2. You can categorize data in B-tree index in descending order as well.
3. This feature can be useful in applications where sorting operations are required.

TEXT INDEX

1. Querying text is different from querying data because words have shades of meaning, relationships to other words, and opposites.
2. You may want to search for words that are near each other, or words that are related to thers.
3. These queries would be extremely difficult if all you had available was the standard relational operators.
4. By extending SQL to include text indexes, oracle text permits you to ask very complex questions about the text.
5. To use oracle text, you need to create a text index on the column in which the text is stored.
6. Text index is a collection of tables and indexes that store information about the text stored in the column.

TYPES

• CONTEXT
• CTXCAT
• CTXRULE

HOW TO CREATE TEXT INDEX ?

• You can create a text index via a special version of the create index comman.
• For context index, specify the ctxsys.context index type and for ctxcat index, specify the ctxsys.ctxcat index type.

TEXT QUERIES

CONTAINS & CATSEARCH

HOW A TEXT QEURY WORKS ?

• When a function such as CONTAINS or CATSEARCH is used in query, the text portion of the query is processed by oracle text.
• The remainder of the query is processed just like a regular query within the database.
• The result of the text query processing and the regular query processing are merged to return a single set of records to the user.
• SEARCHING FOR AN EXACT MATCH OF A WORD The following queries will search for a word called 'prperty' whose score is greater than zero.

SEARCHING FOR AN EXACT MATCH OF MULTIPLE WORDS

SEARCHING FOR AN EXACT MATCH OF A PHRASE

SEARCHING FOR WORDS THAT ARE NEAR EACH OTHER

USING WILDCARDS DURING SEARCHES

SEARCHING FOR WORDS THAT SHARE THE SAME STEM

SEARCHING FOR FUZZY MATCHES

1. A fuzzy match expands the specified search term to include words that are spelled similarly but that do not necessarily have the same word stem. Fuzzy matches are most helpful when the text contains misspellings.
2. The misspellings can be either in the searched text or in the search string specified by the user during the query.
3. The following queries will not return anything because its search does not contain the word 'hardest'.

1.  It does, however, contains the word 'harvest'.
2. A fuzzy match will return the books containing the word 'harvest' even though 'harvest' has a different word stem thant the word used as the search term.
3. To use a fuzzy match, precede the search term with a question mark, with no space between the question mark and the beginning of the search term.

SEARCHING FOR WORDS THAT SOUND LIKE OTHER WORDS

1. SOUNDEX, expands search terms based on how the word sounds.
2. The SOUNDEX expansion method uses the same text-matching logic available via the SOUNDEX function in SQL.
3. To use the SOUNDEX option, you must precede the search term with an exclamation mark(!).

INDEX SYNCHRONIZATION

• When using CONTEXT indexes, you need to manage the text index contents;
• the text indexes are not updated when the base table is updated.
• When the table was updated, its text index is out of sync with the base table.
• To sync of the index, execute the SYNC_INDEX procedure of the CTX_DDL package.

INDEX SETS

• Historically, problems with queries of text indexes have occurred when other criteria are used alongside text searches as part of the where clause.
• To improve the mixed query capability, oracle features index sets.
• The indexes within the index set may be structured relational columns or on text columns.
• To create an index set, use the CTX_DDL package to create the index set and add indexes to it.
• When you create a text index, you can then specify the index set it belongs to.

INDEX-ORGANIZED TABLE

1. An index-organized table keeps its data sorted according to the primary key column values for the table.
2. Index-organized tables store their data as if the entire table was stored in an index.
3. An index-organized table allows you to store the entire table's data in an index.

PARTITION INDEX

• Similar to partitioning tables, oracle allows you to partition indexes too.
• Like table partitions, index partitions could be in different tablespaces.

LOCAL INDEXES

• Local keyword tells oracle to create a separte index for each partition.
• In the local prefixed index the partition key is specified on the left prefix. When the underlying table is partitioned baes on, say two columns then the index can be prefixed on the first column specified.
• Local prefixed indexes can be unique or non unique.
• Local indexes may be easier to manage than global indexes.

GLOBAL INDEXES

• A global index may contain values from multiple partitions.
• An index is global prefixed if it is partitioned on the left prefix of the index columns.
• The global clause allows you to create a non-partitioned index.
• Global indexes may perform uniqueness checks faster than local (partitioned) indexes.
• You cannot create global indexes for hash partitions or subpartitions.

• Similar to table partitions, it is possible to move them from one device to another.
• But unlike table partitions, movement of index partitions requires individual reconstruction of the index or each partition (only in the case of global index).

• Index partitions cannot be dropped manually.
• They are dropped implicitly when the data they refer to is dropped from the partitioned table.

MONITORING USE OF INDEXES

• Once you turned on the monitoring the use of indexes, then we can check whether the table is hitting the index or not.
• To monitor the use of index use the follwing syntax.

DATA MODEL

• ALL_INDEXES
• DBA_INDEXES
• USER_INDEXES
• ALL_IND-COLUMNS
• DBA-IND_COLUMNS
• USER_IND_COLUMNS
• ALL_PART_INDEXES
• DBA_PART_INDEXES
• USER_PART_INDEXES
• V$OBJECT_USAGE

SQL*PLUS COMMNANDS

BREAK

COMPUTE

TTITLE

BTITLE

 
 
   	                           EMPLOYEE DETAILS 
                                ----------------------- 
 
      EMPNO    ENAME    JOB      MGR     HIREDATE     SAL     COMM   DEPTNO 
      ------  ------- --------  -------  ---------  -------- ------ ---------- 
      7782     CLARK  MANAGER     7839   09-JUN-81    2450             10 
      7839     KING   PRESIDENT          17-NOV-81    5000 
      7934     MILLER CLERK       7782   23-JAN-82    1300 
                                                     ---------  ********** 
                                                      8750        sum 
 
      7369     SMITH  CLERK       7902   17-DEC-80     800             20 
      7876     ADAMS  CLERK       7788   23-MAY-87    1100 
      7902     FORD   ANALYST     7566   03-DEC-81    3000 
      7788     SCOTT  ANALYST     7566   19-APR-87    3000 
      7566     JONES  MANAGER     7839   02-APR-81    2975 
                                                    ---------- ********** 
                                                     10875        sum 
 
      7499     ALLEN  SALESMAN    7698   20-FEB-81    1600        300  30 
      7698     BLAKE  MANAGER     7839   01-MAY-81    2850 
      7654     MARTIN SALESMAN    7698   28-SEP-81    1250       1400 
      7900     JAMES  CLERK       7698   03-DEC-81     950 
      7844     TURNER SALESMAN    7698   08-SEP-81    1500          0 
      7521     WARD   SALESMAN    7698   22-FEB-81    1250        500 
                                                     ----------  ********** 
                                                      9400         sum 
                                                     ---------- 
      sum                                            29025 

                       ** THANKQ ** 

CLEAR

CHANGE

 
      DEPTNO      DNAME       LOC 
     ---------- ------------ ----------- 
        10        ACCOUNTING  NEW YORK 
        20        RESEARCH    ALLAS 
        30        SALES       CHICAGO 
        40        OPERATIONS  BOSTON 

COLUMN

SAVE

EXECUTE

SPOOL

 
    DEPTNO  DNAME            LOC 
   ------- ------------   ---------- 
    10      ACCOUNTING     NEW YORK 
    20      RESEARCH       DALLAS 
    30      SALES          CHICAGO 
    40      OPERATIONS     BOSTON 

 
   DEPTNO   DNAME          LOC 
   ------ ------------   ---------- 
    10      ACCOUNTING     NEW YORK 
    20      RESEARCH       DALLAS 
    30      SALES          CHICAGO 
    40      OPERATIONS     BOSTON 

LIST

INPUT

APPEND

DELETE

VARIABLE

PRINT

		DEPT_NAME
		--------------
		ACCOUNTING

START

HOST

SHOW

appinfo is OFF and set to "SQL*Plus"
arraysize 15
autocommit OFF
autoprint OFF
autorecovery OFF
autotrace OFF
blockterminator "." (hex 2e)
btitle OFF and is the first few characters of the next SELECT statement
cmdsep OFF
colsep " "
compatibility version NATIVE
concat "." (hex 2e)
copycommit 0
COPYTYPECHECK is ON
define "&" (hex 26)
describe DEPTH 1 LINENUM OFF INDENT ON
echo OFF
editfile "afiedt.buf"
embedded OFF
escape OFF
FEEDBACK ON for 6 or more rows
flagger OFF
flush ON

RUN

STORE

FOLD_AFTER

 
      10 
   ACCOUNTING 
   NEW YORK 
 
      20 
   RESEARCH 
   DALLAS 
      30 
   SALES 
   CHICAGO 
 
      40 
   OPERATIONS 
   BOSTON 

FOLD_BEFORE

DFINE

 
DEFINE _DATE               = "16-MAY-07" (CHAR) 
DEFINE _CONNECT_IDENTIFIER = "oracle" (CHAR) 
DEFINE _USER              = "SCOTT" (CHAR) 
DEFINE _PRIVILEGE         = "" (CHAR) 
DEFINE _SQLPLUS_RELEASE  = "1001000200" (CHAR) 
DEFINE _EDITOR          = "Notepad" (CHAR) 
DEFINE _O_VERSION      = "Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 -  
                           Production With the Partitioning, OLAP and Data Mining  
                             options" (CHAR) 
DEFINE _O_RELEASE      = "1001000200" (CHAR) 

SET COMMANDS

LINESIZE

PAGESIZE

DESCRIBE

	 
Name           Null?            Type 
---------     -------------   ------------ 
DEPTNO         NOT NULL         NUMBER(2) 
DNAME                           VARCHAR2(14) 
LOC                             VARCHAR2(13) 

PAUSE

• When the displayed data contains hundreds or thousands of lines, when you select it then it will automatically scrolls and displays the last page data.
• To prevent this you can use this pause option.
• By using this it will display the data correspoinding to the pagesize with a break which will continue by hitting the return key.
• By default this will be off.

FEEDBACK

• This will give the information regarding howmany rows you selected the object.
• By default the feedback message will be displayed, only when the object contains more than 5 rows.

 
       DEPTNO    DNAME         LOC 
      -------- -------------- ------------- 
        10       ACCOUNTING    NEW YORK 
        20       RESEARCH      DALLAS 
        30       SALES         CHICAGO 
        40       OPERATIONS    BOSTON 
 
4 rows selected. 

HEADING

• If you want to display data without headings, then you can achieve with this.
• By default heading is on.

 
        10   ACCOUNTING   NEW YORK 
        20   RESEARCH     DALLAS 
        30   SALES        CHICAGO 
        40   OPERATIONS   BOSTON 

SERVEROUTPUT

• This will be used to display the output of the PL/SQL programs.
• By default this will be off.

TIME

• This will be used to display the time.
• By default this will be off.

	
19:56:33 SQL>

TIMING

• This will give the time taken to execute the current SQL statement.
• By default this will be off.

 
      DEPTNO    DNAME       LOC 
     -------- ---------- ------------- 
        10   ACCOUNTING    NEW YORK 
        20   RESEARCH      DALLAS 
        30   SALES         CHICAGO 
        40   OPERATIONS    BOSTON 
 
Elapsed: 00:00:00.06 

SQLPROMPT

 
ORACLE> 

SQLCASE

• This will be used to change the case of the SQL statements.
• By default the case is mixed.

SQLTERMINATOR

• This will be used to change the terminator of the SQL statements.
• By default the terminator is ;.

DEFINE

• By default if the & character finds then it will treat as bind variable and ask for the input.
•  Suppose your want to treat it as a normal character while inserting data, then you can prevent this by using the define option.
•  By default this will be on

	
Enter value for d: 
old   1: insert into dept values(50,'R&D','HYD')
new   1: INSERT INTO DEPT VALUES(50,'R','HYD')

NEWPAGE

• This will shows how many blank lines will be left before the report.
• By default it will leave one blank line.

• The zero value for newpage does not produce zero blank lines instead it switches to a special property which produces a top-of-form character (hex 13) just before the date on each page.
  
• Most modern printers respond to this by moving immediately to the top of the next page, where the priting of the report will begin.

HEADSEP

• This allow you to indicate where you want to break a page title or a column heading that runs longer than one line.
• The default heading separator is vertical bar (|).

 
      DEPTNO    DNAME       LOC 
     ------- -----------  ------------- 
        10   ACCOUNTING   NEW YORK 
        20   RESEARCH     DALLAS 
        30   SALES        CHICAGO 
        40   OPERATIONS   BOSTON 

 
                 DEPARTMENT 

      DEPTNO       NAME             LOC 
     ---------- --------------   ---------- 
        10       ACCOUNTING       NEW YORK 
        20       RESEARCH         DALLAS 
        30       SALES            CHICAGO 
        40       OPERATIONS       BOSTON 

ECHO

• When using a bind variable, the SQL statement is maintained by echo.
• By default this is off.

VERIFY

• When using a bind variable, the old and new statements will be maintained by verify.
• By default this is on.

 
Enter value for dno: 10 
old   1: select * from dept where deptno = &dno 
new   1: select * from dept where deptno = 10 
 
        DEPTNO    DNAME           LOC 
       -------- ------------   ----------- 
        10       ACCOUNTING      NEW YORK 

 
Enter value for dno: 20 
 
        DEPTNO    DNAME      LOC 
       -------- ----------  ----------- 
        20       RESEARCH    DALLAS 

PNO

• This will give displays the page numbers.
• By default the value would be zero.

  
09-JUN-81                                              page  1  
  
 EMPNO  ENAME     JOB         MGR     SAL  COMM     DEPTNO  
 ------ -------- ---------- -------  ----- -----   --------  
 7782   CLARK     MANAGER     7839    2450            10  
 7839   KING      PRESIDENT           5000            10  
 7934   MILLER    CLERK       7782    1300            10  

• In the above noprint tells SQLPLUS not to display this column when it prints the results of the SQL statement.
  
• Dates that have been reformatted by TO_CHAR get a default width of about 100 characters. By changing the format to a1 trunc, you minimize this effect.
  
• NEW_VALUE inserts contents of the column retrieved by the SQL statement into a variable called xtoday.

SPECIAL FILES

LOGIN.sql

• If you would like SQLPLUS to define your own environmental settings, put all the required commands in a file named login.sql.
• This is a special filename that SQLPLUS always looks for whenever it starts up.
• If it finds login.sql, it executes any commands in it as if you had entered then by hand.
• You can put any command in login.sql that you can use in SQLPLUS, including SQLPLUS commands and SQL statements.
• All to them executed before SQLPLUS gives you the SQL> prompt.

GLOGIN.sql

IMP QUERIES

1. To find the nth row of a table
   SQL> Select *from emp where rowid = (select max(rowid) from emp where rownum <= 4);          Or
   SQL> Select *from emp where rownum <= 4 minus select *from emp where rownum <= 3;
2. To find duplicate rows
   SQL> Select *from emp where rowid in (select max(rowid) from emp group by empno, ename, mgr, job, hiredate, comm, deptno, sal);          Or
   SQL> Select empno,ename,sal,job,hiredate,comm , count(*) from emp group by empno,ename,sal,job,hiredate,comm having count(*) >=1;
3. To delete duplicate rows
   SQL> Delete emp where rowid in (select max(rowid) from emp group by empno,ename,mgr,job,hiredate,sal,comm,deptno);
4. To find the count of duplicate rows
   SQL> Select ename, count(*) from emp group by ename having count(*) >= 1;
5. How to display alternative rows in a table ?
   SQL> select *from emp where (rowid,0) in (select rowid,mod(rownum,2) from emp);
6. Getting employee details of each department who is drawing maximum sal ?
   SQL> select *from emp where (deptno,sal) in ( select deptno,max(sal) from emp group by deptno);
7. How to get number of employees in each department , in which department is having more than 2500 employees ?
   SQL> Select deptno,count(*) from emp group by deptno having count(*) >2500;
8. To reset the time to the beginning of the day
   SQL> Select to_char(trunc(sysdate),'dd-mon-yyyy hh:mi:ss am') from dual;
9. To find nth maximum sal
   SQL> Select *from emp where sal in (select max(sal) from (select *from emp order by sal) where rownum <= 5);

INTRODUCTION

• Highly structured, readable and accessible language.
• Standard and Protable language.
• Embedded language.
• Improved execution authority.

10g FEATURES

• Optimized compiler

  To change the optimizer settings for the entire database, set the database parameter PLSQL_OPTIMIZE_LEVEL. Valid settings are as follows

  0 - No optimization
  1 - Moderate optimization
  2 - Aggressive optimization

  These settings are also modifiable for the current session.
  SQL> alter session set plsql_optimze_level=2;

  Oracle retains optimizer settings on a module-by-module basis. When you recompile a particular module with nondefault settings, the settings will stick allowing you to recompile later on using REUSE SETTINGS.

  
  SQL> Alter procedure proc compile plsql_optimize_level=1;
  SQL> Alter procedure proc compile reuse settings;
  
• Compile-time warnings.

  Starting with oracle database 10g release 1 you can enable additional compile-time warnings to help make your programs more robust. The compiler can detect potential runtime problems with your code, such as identifying lines of code that will never be run. This process, also known as lint checking.
  To enable these warnings for the entire database, set the database parameter PLSQL_WARNINGS. These settings are also modifiable for the current session.

  
  SQL> alter session set plsql_warnings = 'enable:all'; The above can be achieved using the built-in package DBMS_WARNING.

• Conditional compilation.

  Conditional compilation allows the compiler to allow to compile selected parts of a program based on conditions you provide with the $IF directive.

• Support for non-sequential collections in FORALL.
• Improved datatype support.
• Backtrace an exception to its line number.

  When handling an error, how can you find the line number on which the error was originally raised ?
  In earlier release, the only way to do this was allow you exception to go unhandled and then view the full error trace stack.
  Now you can call DBMS_UTILITY.FORMAT_ERROR_BACKTRACE function to obtain that stack and manipulate it programmatically within your program.

• Set operators for nested tables.
• built-in functions.
  • REGEXP_LIKE
  • REGEXP_INSTR
  • REGEXP_SUBSTR
  • REGEXP_REPLACE
• Programmer-defined quoting mechanism.

  Starting with oracle database 10g release 1, you can define your own quoting mechanism for string literals in both SQL and PL/SQL.

  Use the characters q'(q followed by a single quote) to note the programmer-defined deliemeter for you string literal.

  
  Ex:

   DECLARE 
       v varchar(10) := 'computer'; 
  BEGIN 
       dbms_output.put_line(q'*v = *' || v); 
       dbms_output.put_line(q'$v = $' || v); 
  END; 
   
  Output: 
  	v = computer 
  v = computer 
  

• Many new built-in packages.

  DBMS_SCHEDULER

  Represents a major update to DBMS_JOB. DBMS_SCHEDULER provides much improved functionality for scheduling and executing jobs defined via stored procedures.

  DBMS_CRYPTO

  Offers the ability to encrypt and decrypt common oracle datatype, including RAWs, BLOBs, and CLOBs. It also provides globalization support for encrypting data across different charactersets.

  DBMS_MONITOR

  Provides an API to control additional tracing and statistics gathering of sessions.

  DBMS_WARNING

  Provides an API into the PL/SQL compiler warnings module, allowing you to read and change settings that control which warnings are suppressed, displayed, or treated as errors.

  STANDARD PACKAGE

  Oracle has defined in this special package. Oracle defines quite a few identifiers in this package, including built-in exceptions, functions and subtypes. You can reference the built-in form by prefixing it with STANDARD.

  The basic unit in any PL/SQL program is block. All PL/SQL programs are composed of blocks which can occur sequentially or nested.

  BLOCK STRUCTURE

  Declare
  -- declarative section
  Begin
  -- executable section
  Exception
  -- exception section
  End;
  

  In the above declarative and exceptiona sections are optional.

• Anonymous blocks
• Named blocks
  • Labeled blocks
  • Subprograms
  • Triggers

ANONYMOUS BLOCKS

	BEGIN
	     Dbms_output.put_line('My first program'):
	END;

LABELED BLOCKS

	<<my_bloock>>
	BEGIN
      Dbms_output.put_line('My first program'):
	END;

SUBPROGRAMS

Subprograms are procedures and functions. They can be stored in the database as stand-alone objects, as part of package or as methods of an object type.

TRIGGERS

Triggers consists of a PL/SQL block that is associated with an event that occur in the database.

NESTED BLOCKS

A block can be nested within the executable or exception section of an outer block.

IDENTIFIERS

Identifiers are used to name PL/SQL objects, such as variables, cursors, types and subprograms. Identifiers consists of a letter, optionally followed by any sequence of characters, including letters, numbers, dollar signs, underscores, and pound signs only. The maximum length for an identifier is 30 characters.

QUOTED IDENTIFIERS

If you want to make an identifier case sensitive, include characters such as spaces or use a reserved word, you can enclose the identifier in double quotation marks.

       		  DECLARE
        "a" number := 5;
        "A" number := 6;
  BEGIN
        dbms_output.put_line('a = ' || a);
        dbms_output.put_line('A = ' || A);
  END;        
Output:
  a = 6
  A = 6

COMMENTS

• Single line comments
• Multiline comments

SINGLE LINE COMMENTS

 
		BEGIN 
		     Dbms_output.put_line('hello');   -- sample program 
		END; 

MULTILINE COMMENTS

 
		BEGIN 
		     Dbms_output.put_line('hello');   /* sample program */ 
		END; 

VARIABLE DECLERATIONS

DECLARE
      a number;
      b number := 5;
      c number default 6;

CONSTANT DECLERATIONS

DECLARE
      b constant number := 5;
      c constant number default 6;

NOT NULL CLAUSE

DECLARE
      b constant number not null:= 5;
      c number not null default 6;

ANCHORED DECLERATIONS

• Scalar anchoring
• Record anchoring

SCALAR ANCHORING

		DECLARE 
		      dno dept.deptno%type; 
     		      Subtype t_number is number; 
                           a t_number; 
		      Subtype t_sno is student.sno%type; 
		      V_sno t_sno; 

RECORD ANCHORING

		DECLARE 
		        V_dept dept%rowtype; 

BENEFITS OF ANCHORED DECLARATIONS

• Synchronization with database columns.
• Normalization of local variables.

PROGRAMMER-DEFINED TYPES

• Constrained
• Unconstrained

CONSTRAINED SUBTYPE

UNCONSTRAINED SUBTYPE

DATATYPE CONVERSIONS

• Explicit conversion
• Implicit conversion

EXPLICIT CONVERSION

IMPLICIT CONVERSION

		DECLARE
     a varchar(10);
BEGIN
     select deptno into a from dept where dname='ACCOUNTING';
END;

• Characters and numbers
• Characters and dates

VARIABLE SCOPE AND VISIBILITY

The scope of a variable is the portion of the program in which the variable can be accessed. For PL/SQL variables, this is from the variable declaration until the end of the block. When a variable goes out of scope, the PL/SQL engine will free the memory used to store the variable.

The visibility of a variable is the portion of the program where the variable can be accessed without having to qualify the reference. The visibility is always within the scope. If it is out of scope, it is not visible.

 
		DECLARE 
		       a number;	-- scope of a 
		BEGIN 
		-------- 
     DECLARE 
         b number;	-- scope of b 
     BEGIN 
    ----- 
     END; 
		------ 
		END; 

 
DECLARE 
		      a number;	 
                           b number; 
		BEGIN 
		      -- a , b available here 
       DECLARE 
          b char(10);	 
       BEGIN 
          -- a and char type b is available here 
       END; 
            	      ----- 
		END; 

 
<<my_block>> 
DECLARE 
      a number;	 
      b number; 
BEGIN 
          -- a , b available here 
DECLARE 
      b char(10);	 
BEGIN 
       -- a and char type b is available here 
       -- number type b is available using <<my_block>>.b 
END; 
        ------ 
END; 

PL/SQL CONTROL STRUCTURES

• If-then-else
• Case
• Case with no else
• Labeled case
• Searched case
• Simple loop
• While loop
• For loop
• Goto and Labels

IF-THEN-ELSE

	If <condition1> then 
	    Sequence of statements; 
	Elsif <condition1> then 
                   Sequence of statements; 
	...... 
	Else 
	      Sequence of statements; 
	End if; 

DECLARE
       dno number(2);
BEGIN
       select deptno into dno from dept where dname = 'ACCOUNTING';
       if dno = 10 then
          dbms_output.put_line('Location is NEW YORK');
       elsif dno = 20 then
               dbms_output.put_line('Location is DALLAS');
       elsif dno = 30 then
               dbms_output.put_line('Location is CHICAGO');
       else
               dbms_output.put_line('Location is BOSTON');
       end if;
END;


Output:
		Location is NEW YORK

CASE

	Case test-variable
		When value1 then sequence of statements;
		When value2 then sequence of statements;
		......
		When valuen then sequence of statements;
		Else sequence of statements;
	End case;

DECLARE
      dno number(2);
BEGIN
       select deptno into dno from dept where dname = 'ACCOUNTING';
       case dno
               when 10 then
                         dbms_output.put_line('Location is NEW YORK');
               when 20 then
                         dbms_output.put_line('Location is DALLAS');
               when 30 then
                         dbms_output.put_line('Location is CHICAGO');
               else
                         dbms_output.put_line('Location is BOSTON');
        end case;
END;

Output:
		Location is NEW YORK

CASE WITHOUT ELSE

	Case test-variable
		When value1 then sequence of statements;
		When value2 then sequence of statements;
		......
		When valuen then sequence of statements;
	End case;

DECLARE
       dno number(2);
BEGIN
       select deptno into dno from dept where dname = 'ACCOUNTING';
       case dno
               when 10 then
                         dbms_output.put_line('Location is NEW YORK');
               when 20 then
                         dbms_output.put_line('Location is DALLAS');
               when 30 then
                         dbms_output.put_line('Location is CHICAGO');
               when 40 then
                         dbms_output.put_line('Location is BOSTON');
               end case;
END;

Output:
		Location is NEW YORK

LABELED CASE

	<<label>>
Case test-variable
		When value1 then sequence of statements;
		When value2 then sequence of statements;
		......
		When valuen then sequence of statements;
	End case;

DECLARE
       dno number(2);
BEGIN
       select deptno into dno from dept where dname = 'ACCOUNTING';
       <<my_case>>
       case dno
               when 10 then
                         dbms_output.put_line('Location is NEW YORK');
               when 20 then
                         dbms_output.put_line('Location is DALLAS');
               when 30 then
                         dbms_output.put_line('Location is CHICAGO');
               when 40 then
                         dbms_output.put_line('Location is BOSTON');
        end case my_case;
END;

Output:
		Location is NEW YORK

SEARCHED CASE

	Case
		When <condition1> then sequence of statements;
		When <condition2> then sequence of statements;
		......
		When <conditionn> then sequence of statements;
	End case;

DECLARE
        dno number(2);
BEGIN
        select deptno into dno from dept where dname = 'ACCOUNTING';
        case dno
                 when dno = 10 then
                           dbms_output.put_line('Location is NEW YORK');
                 when dno = 20 then
                           dbms_output.put_line('Location is DALLAS');
                 when dno = 30 then
                           dbms_output.put_line('Location is CHICAGO');
                 when dno = 40 then
                           dbms_output.put_line('Location is BOSTON');
        end case;
END;

Output:
		Location is NEW YORK

SIMPLE LOOP

	Loop
	Sequence of statements;
	Exit when <condition>;
	End loop;

	If <condition> then
		Exit;
	End if;

		DECLARE
      i number := 1;
BEGIN
      loop
          dbms_output.put_line('i = ' || i);
          i := i + 1;
          exit when i > 5;
      end loop;
END;

Output:
		i = 1
i = 2
i = 3
i = 4
i = 5

WHILE LOOP

	While <condition> loop
	Sequence of statements;
	End loop;

		DECLARE
     i number := 1;
BEGIN
     While i <= 5 loop
               dbms_output.put_line('i = ' || i);
               i := i + 1;
      end loop;
END;

Output:
		i = 1
i = 2
i = 3
i = 4
i = 5

FOR LOOP

	For <loop_counter_variable> in low_bound..high_bound loop
	Sequence of statements;
	End loop;

BEGIN
     For i in 1..5 loop
            dbms_output.put_line('i = ' || i);
      end loop;
END;
Output:
		i = 1
i = 2
i = 3
i = 4
i = 5

BEGIN
     For i in reverse 1..5 loop
            dbms_output.put_line('i = ' || i);
     end loop;
END;
Output:
		i = 5
i = 4
i = 3
i = 2
i = 1

NULL STATEMENT

• Improving program readability: Sometimes, it is helpful to avoid any ambiguity inherent in an IF statement that doesn't cover all possible cases. For example, when you write an IF statement, you do not have to include an ELSE clause.
• Nullifying a raised exception: When you don't want to write any special code to handle an exception, you can use the NULL statement to make sure that a raised exception halts execution of the current PL/SQL block but does not propagate any exceptions to enclosing blocks.
• Using null after a label: In some cases, you can pair NULL with GOTO to avoid having to execute additional statements. For example, I use a GOTO statement to quickly move to the end of my program if the state of my data indicates that no further processing is required. Because I do not have to do anything at the termination of the program, I place a NULL statement after the label because at least one executable statement is required there. Even though NULL deos nothing, it is still an executable statement.

GOTO AND LABELS

	Goto label;

BEGIN
     For i in 1..5 loop
            dbms_output.put_line('i = ' || i);
            if i = 4 then
               goto exit_loop;
            end if;
     end loop;
     <<exit_loop>>
     Null;
END;

Output:
		i = 1
i = 2
i = 3
i = 4

• It is illegal to branch into an inner block, loop.
• At least one executable statement must follow.
• It is illegal to branch into an if statement.
• It is illegal to branch from one if statement to another if statement.
• It is illegal to branch from exception block to the current block.

PRAGMAS

	PRGAMA instruction_to_compiler.

• AUTONOMOUS_TRANSACTION
• EXCEPTION_INIT
• RESTRICT_REFERENCES
• SERIALLY_REUSABLE

SUBPROGRAMS

PROCEDURES

	Procedure [schema.]name [(parameter1 [,parameter2 ...])]  
                            [authid definer | current_user] is 
		-- [declarations] 
          Begin 
		-- executable statements 
          [Exception 
		-- exception handlers] 
          End [name]; 
 

FUNCTIONS

	Function [schema.]name [(parameter1 [,parameter2 ...])] 
                          Return return_datatype
                          [authid definer | current_user] 
                          [deterministic]
                          [parallel_enable] is
		-- [declarations]
          Begin
		-- executable statements
          [Exception
		-- exception handlers]
          End [name];

In the above authid clause defines whether the procedure will execute under the authority of the definer of the procedure or under the authority of the current user.

Deterministic clause defines, an optimization hint that lets the system use a saved copy of the function's return result, if available. The quety optimizer can choose whether to use the saved copy or re-call the function.

Parallel_enable clause defines, an optimization hint that enables the function to be executed in parallel when called from within SELECT statement.

PARAMETER MODES

• In (Default)
• Out
• In out

IN

OUT

• Out parameter will act as unintialized variable.
• You cannot provide a default value to an out parameter.
• Any assignments made to out parameter are rolled back when an exception is raised in the program.
• An actual parameter corresponding to an out formal parameter must be a variable.

IN OUT

• In out parameter will act as initialized variable.
• An actual parameter corresponding to an in out formal parameter must be a variable.

DEFAULT PARAMETERS

• Default Parameters will not allow in the beginning and middle.
• Out and In Out parameters can not have default values.

procedure p(a in number default 5, b in number default 6, c in number default 7) - valid

procedure p(a in number, b in number default 6, c in number default 7) - valild

procedure p(a in number, b in number, c in number default 7) - valild

procedure p(a in number, b in number default 6, c in number) - invalild

procedure p(a in number default 5, b in number default 6, c in number) - invalild

procedure p(a in number default 5, b in number, c in number) - invalild

NOTATIONS

• Positional notation
• Name notation

FORMAL  AND  ACTUAL  PARAMETERS

• Parametes which are in calling subprogram are actual parameters.
• Parametes which are in called subprogram are formal parameters.
• If any subprogram was called, once the call was completed then the values of formal parameters are copied to the actual parameters.

CREATE OR REPLACE PROCEDURE SAMPLE(a in number,b out number,c in out number) is
BEGIN
     dbms_output.put_line('After call');
     dbms_output.put_line('a = ' || a ||' b = ' || b || ' c = ' || c);
     b := 10;
     c := 20;
     dbms_output.put_line('After assignment');
     dbms_output.put_line('a = ' || a ||' b = ' || b || ' c = ' || c);
END SAMPLE;

DECLARE
     v1 number := 4;
     v2 number := 5;
     v3 number := 6;
BEGIN
     dbms_output.put_line('Before call');
     dbms_output.put_line('v1 = ' || v1 || ' v2 = ' || v2 || ' v3 = ' || v3);
     sample(v1,v2,v3);
     dbms_output.put_line('After completion of call');
     dbms_output.put_line('v1 = ' || v1 || ' v2 = ' || v2 || ' v3 = ' || v3);
END;

Output:
Before call
v1 = 4 v2 = 5 v3 = 6
After call
a = 4 b =  c = 6
After assignment
a = 4 b = 10 c = 20
After completion of call
v1 = 4 v2 = 10 v3 = 20

CREATE OR REPLACE FUN(a in number,b out number,c in out number) return number IS
BEGIN
     dbms_output.put_line('After call');
     dbms_output.put_line('a = ' || a || ' b = ' || b || ' c = ' || c);
      dbms_output.put_line('Before assignement Result = ' || (a*nvl(b,1)*c));
      b := 5;
      c := 7;
      dbms_output.put_line('After assignment');
      dbms_output.put_line('a = ' || a || ' b = ' || b || ' c = ' || c);
      return (a*b*c);
 END FUN;

DECLARE
      v1 number := 1;
      v2 number := 2;
      v3 number := 3;
      v number;
BEGIN
      dbms_output.put_line('Before call');
      dbms_output.put_line('v1 = ' || v1 || ' v2 = ' || v2 || ' v3 = ' || v3);
      v := fun(v1,v2,v3);
      dbms_output.put_line('After call completed');
      dbms_output.put_line('v1 = ' || v1 || ' v2 = ' || v2 || ' v3 = ' || v3);
      dbms_output.put_line('Result = ' || v);
END;

Output:
Before call
v1 = 1 v2 = 2 v3 = 3
After call
a = 1 b =  c = 3
Before assignement Result = 3
After assignment
a = 1 b = 5 c = 7
After call completed
v1 = 1 v2 = 5 v3 = 7
Result = 35

RESTRICTIONS ON FORMAL PARAMETERS

• By declaring with specified size in actual parameters.
• By declaring formal parameters with %type specifier.

USING NOCOPY

• Nocopy is a hint, not a command. This means that the compiler might silently decide that it can't fulfill your request for a nocopy parameter.
• The copying from formal to actual can be restricted by issuing nocopy qualifier.
• To pass the out and in out parameters by reference use nocopy qualifier.

	 CREATE OR REPLACE PROCEDURE PROC(a in out nocopy number) IS
       BEGIN
      ----
        END PROC;

CALL  AND  EXEC

• The parantheses are always required, even if the subprogram takes no arguments.
• We can not use call with out and in out parameters.
• Call is a SQL statement, it is not valid inside a PL/SQL block;
• The INTO clause is used for the output variables of functions only.
• We can not use 'exec' with out or in out parameters.
• Exec is not valid inside a PL/SQL block;

CREATE OR REPLACE PROC IS
BEGIN
            dbms_output.put_line('hello world');
END PROC;
Output:

 SQL> call proc();
        hello world

CREATE OR REPLACE PROC(a in number,b in number) IS
BEGIN
      dbms_output.put_line('a = ' || a || ' b = ' || b);
END PROC;

Output:

 SQL> call proc(5,6);
        a = 5 b = 6

CREATE OR REPLACE FUNCTION FUN RETURN VARCHAR IS
BEGIN
      return 'hello world';
END FUN;

Output:

 SQL> variable v varchar(20)

 SQL> call fun() into :v;

 SQL> print v
        hello world

CALL BY REFERENCE AND CALL BY VALUE

• In parameters by default call by reference where as out and in out call by value.
• When parameter passed by reference, a pointer to the actual parameter is passed to the corresponding formal parameter.
• When parameter passed by value it copies the value of the actual parameter to the formal parameter.
• Call by reference is faster than the call by value because it avoids the copying.

SUBPROGRAMS  OVERLOADING

• Possible with different number of parameters.
• Possible with different types of data.
• Possible with same type with objects.
• Can not be possible with different types of modes.
• We can overload local subprograms also.

DECLARE
     i t1 := t1(5);
     j t2 := t2(5);
      PROCEDURE P(m t1) IS
      BEGIN
         dbms_output.put_line('a = ' || m.a);
      END P;
      PROCEDURE P(n t2) IS
      BEGIN
         dbms_output.put_line('b = ' || n.b);
      END P;
      PROCEDURE PRODUCT(a number,b number) IS
      BEGIN
         dbms_output.put_line('Product of a,b = ' || a * b);
      END PRODUCT;
      PROCEDURE PRODUCT(a number,b number,c number) IS
      BEGIN
         dbms_output.put_line('Product of a,b = ' || a * b * c);
      END PRODUCT;
BEGIN
     p(i);
     p(j);
     product(4,5);
     product(4,5,6);
END;


Output:
a = 5
b = 5
Product of a,b = 20
Product of a,b = 120

BENEFITS OF OVERLOADING

• Supporting many data combinations
• Fitting the program to the user.

RESTRICTIONS  ON  OVERLOADING

• Overloaded programs with parameter lists that differ only by name must be called using named notation.
• The parameter list of overloaded programs must differ by more than parameter mode.
• All of the overloaded programs must be defined within the same PL/SQL scope or block.
• Overloaded functions must differ by more than their return type.

IMPORTANT  POINTS  ABOUT  SUBPROGRAMS

• When a stored subprogram is created, it is stored in the data dictionary.
• The subprogram is stored in compile form which is known as p-code in addition to the source text.
• The p-code has all of the references in the subprogram evaluated, and the source code is translated into a form that is easily readable by PL/SQL engine.
• When the subprogram is called, the p-code is read from the disk, if necessary, and executed.
• Once it reads from the disk, the p-code is stored in the shared pool portion of the system global area (SGA), where it can be accessed by multiple users as needed.
• Like all of the contents of the shared pool, p-code is aged out of the shared pool according to a least recently used (LRU) algorithm.
• Subprograms can be local.
• Local subprograms must be declared in the declarative section of PL/SQL block and called from the executable section.
• Subprograms can not have the declarative section separately.
• Stored subprograms can have local subprograms;
• Local subprograms also can have local subprograms.
• If the subprogram contains a variable with the same name as the column name of the table then use the dot method to differentiate (subprogram_name.sal).
• Subprograms can be invalidated.

PROCEDURES  Vs  FUNCTIONS

• Procedures may return through out and in out parameters where as function must return.
• Procedures can not have return clause where as functions must.
• We can use call statement directly for executing procedure where as we need to declare a variable in case of functions.
• Functions can use in select statements where as procedures can not.
• Functions can call from reports environment where as procedures can not.
• We can use exec for executing procedures where as functions can not.
• Function can be used in dbms_output where as procedure can not.
• Procedure call is a standalone executable statement where as function call is a part of an executable statement.

STORED  Vs  LOCAL SUBPROGRAMS

• The stored subprogram is stored in compiled p-code in the database, when the procedure is called it does not have to be compiled. The local subprogram is compiled as part of its containing block. If the containing block is anonymous and is run multiple times, the subprogram has to be compiled each time.
• Stored subprograms can be called from any block submitted by a user who has execute privileges on the subprogram. Local subprograms can be called only from the block containing the subprogram.
• By keeping the stored subprogram code separate from the calling block, the calling block is shorter and easier to understand. The local subprogram and the calling block are one and the same, which can lead to part confusion. If a change to the calling block is made, the subprogram will be recompiled as of the recompilation of the containing block.
• The compiled p-code can be pinned in the shared pool using the DBMS_SHARED_POOL Package. This can improve performance. Local subprograms cannot be pinned in the shared pool by themselves.
• Stand alone stored subprograms can not be overloaded, but packaged subprograms can be overloaded within the same package.
• Local subprograms can be overloaded within the same block.

CREATE OR REPLACE PROCEDURE P IS
BEGIN
    dbms_output.put_line('Stored subprogram');
END;

Output:

 SQL> exec p
Stored subprogram

DECLARE
      PROCEDURE P IS
     BEGIN
          dbms_output.put_line('Local subprogram');
      END;
BEGIN
     p;
END;

Output:
Local subprogram

COMPILING SUBPROGRAMS

SUBPROGRAMS  DEPENDECIES

• A stored subprogram is marked as invalid in the data dictionary if it has compile errors.
• A stored subprogram can also become invalid if a DDL operation is performed on one of its dependent objects.
• If a subprogram is invalidated, the PL/SQL engine will automatically attempt to recompile in the next time it is called.
• If we have two procedures like P1 and P2 in which P1 depends on P2. If we compile P2 then P1 is invalidated.

SUBPROGRAMS  DEPENDENCIES  IN  REMOTE  DATABASES

• We will call remote subprogram using connect string like P1@ORACLE;
• If we have two procedures like P1 and P2 in which P1 depends on P2 but P2 was in remote database. If we compile P2 it will not invalidate P1 immediately because the data dictionary does not track remote dependencies.
• Instead the validity of remote objects is checked at runtime. When P1 is called, the remote data dictionary is queried to determine the status of P2.
• P1 and P2 are compared to see it P1 needs to be recompiled, there are two different methods of comparision
  • Timestamp Model
  • Signature Model

TIMESTAMP  MODEL

• This is the default model used by oracle.
• With this model, the timestamps of the last modifications of the two objects are compared.
• The last_ddl_time field of user_objects contains the timestamp.
• If the base object has a newer timestamp than the dependent object, the dependent object will be recompiled.

ISSUES WITH THIS MODEL

• If the objects are in different time zones, the comparison is invalid.
• When P1 is in a client side PL/SQL engine such as oracle forms, in this case it may not possible to recompile P1, because the source for it may not be included with the forms.

SIGNATURE MODEL

• When a procedure is created, a signature is stored in the data dictionary in addition to the p-code.
• The signature encodes the types and order of the parametes.
• When P1 is compiled the first time, the signature of P2 is included. Thus, P1 only needs to recompiled when the signature of P2 changes.
• In order to use the signature model, the parameter REMOTE_DEPENDENCIES_MODE must be set to SIGNATURE. This is a parameter in the database initialization file.

THREE WAYS OF SETTING THIS MODE

• Add the line REMOTE_DEPENDENCIES_MODE=SIGNATURE to the database initialization file. The next time the database is started, the mode will be set to SIGNATURE for all sessions.
• Alter system set remote_dependencies_mode = signature; This will affect the entire database (all sessions) from the time the statement is issued. You must have the ALTER SYSTEM privilege to issue this command.
• Alter session set remote_dependencies_mode = signature; This will only affect your session

ISSUES WITH THIS MODEL

• Signatures don't get modified if the default values of formal parameters are changed.
• Suppose P2 has a default value for one of its parameters, and P1 is using this default value. If the default in the specification for P2 is changed, P1 will not be recompiled by default. The old value for the default parameter will still be used until P1 is manually recompiled.
• If P1 is calling a packaged procedure P2, and a new overloaded version of P2 is added to the remote package, the signature is not changed. P1 will still use the old version (not the new overloaded one) until P1 is recompiled manually.

FORWARD DECLERATION

DECLARE
      PROCEDURE P1 IS
      BEGIN
         dbms_output.put_line('From procedure p1');
         p2;
      END P1;
      PROCEDURE P2 IS
      BEGIN
         dbms_output.put_line('From procedure p2');
         p3;
      END P2;
      PROCEDURE P3 IS
      BEGIN
         dbms_output.put_line('From procedure p3');
      END P3;
BEGIN
     p1;
END;

Output:
p2;
*
ERROR at line 5:
ORA-06550: line 5, column 1:
PLS-00313: 'P2' not declared in this scope
ORA-06550: line 5, column 1:
PL/SQL: Statement ignored
ORA-06550: line 10, column 1:
PLS-00313: 'P3' not declared in this scope
ORA-06550: line 10, column 1:
PL/SQL: Statement ignored

DECLARE
      PROCEDURE P2;   --  forward declaration
      PROCEDURE P3;   
      PROCEDURE P1 IS
      BEGIN
         dbms_output.put_line('From procedure p1');
         p2;
      END P1;
      PROCEDURE P2 IS
      BEGIN
         dbms_output.put_line('From procedure p2');
         p3;
      END P2;
      PROCEDURE P3 IS
      BEGIN
         dbms_output.put_line('From procedure p3');
      END P3;
BEGIN
     p1;
END;

Output:
From procedure p1
From procedure p2
From procedure p3

• For stored subprograms and packages the relevant privilege is EXECUTE.
• If user A had the procedure called emp_proc then user A grants execute privilege on procedure to user B with the following command.
  SQL> Grant execute on emp_proc to user B.
• Then user B can run the procedure by issuing
  SQL> Exec user A.emp_proc

CREATE OR REPLACE PROCEDURE P IS
     cursor is select *from student1;
BEGIN
     for v in c loop
           insert into student2 values(v.no,v.name,v.marks);
     end loop;
END P;

HOW TO POPULATE USER B's TABLE

• Oracle introduces Invoker's and Definer's rights.
• By default it will use the definer's rights.
• An invoker's rights routine can be created by using AUTHID clause to populate the userB's table.
• It is valid for stand-alone subprograms, package specifications, and object type specifications only.

 
CREATE OR REPLACE PROCEDURE P 
AUTHID CURRENT_USER IS 
      cursor is select *from student1; 
BEGIN 
      for v in c loop 
            insert into student2 values(v.no,v.name,v.marks); 
      end loop; 
END P; 

CREATE OR REPLACE PROCEDURE P IS
      cursor c is select *from saketh.student;
BEGIN
      for v in c loop
            dbms_output.put_line('No = ' || v.no);
      end loop;
END P;

CREATE OR REPLACE PROCEDURE P IS
      cursor c is select *from saketh.student;
BEGIN 
      for v in c loop
            dbms_output.put_line('No = ' || v.no);
      end loop;
END P;

• The above code will raise error instead of creating procedure .
• This is because of early binding which PL/SQL uses by default in which references are evaluated in compile time but when you are using a role this will affect immediately.

ISSUES WITH INVOKER'S RIGHTS

• In an invoker's rights routine, external references in SQL statements will be resolved using the caller's privilege set.
• But references in PL/SQL statements are still resolved under the owner's privilege set.

TRIGGERS, VIEWS AND INVOKER'S RIGHTS

• A database trigger will always be executed with definer's rights and will execute under the privilege set of the schema that owns the triggering table.
• This is also true for PL/SQL function that is called from a view. In this case, the function will execute under the privilege set of the view's owner.

PACKAGES

• A package is a container for related objects.
• It has specification and body.
• Each of them is stored separately in data dictionary.

PACKAGE SYNTAX

 
Create or replace package <package_name> is 
	-- package specification includes subprograms signatures, 
              cursors and global or public variables. 
End <package_name>; 

Create or replace package body <package_name> is
         -- package body includes body for all the subprograms declared 
           in the spec, private Variables and cursors.
      Begin
	-- initialization section
      Exception
	-- Exception handling seciton
      End <package_name>;

IMPORTANT POINTS ABOUT PACKAGES

• The first time a packaged subprogram is called or any reference to a packaged variable or type is made, the package is instantiated.
• Each session will have its own copy of packaged variables, ensuring that two sessions executing subprograms in the same package use different memory locations.
• In many cases initialization needs to be run the first time the package is instantiated within a session. This can be done by adding initialization section to the package body after all the objects.
• Packages are stored in the data dictionary and can not be local.
• Packaged subprograms has an advantage over stand alone subprogram.
• When ever any reference to package, the whole package p-code was stored in shared pool of SGA.
• Package may have local subprograms.
• You can include authid clause inside the package spec not in the body.
• The execution section of a package is know as initialization section.
• You can have an exception section at the bottom of a package body.
• Packages subprograms are not invalidated.

COMPILING PACKAGES

• SQL> Alter package PKG compile;
• SQL> Alter package PKG compile specification;
• SQL> Alter package PKG compile body;

PACKAGE DEPENDENCIES

• The package body depends on the some objects and the package header.
• The package header does not depend on the package body, which is an advantage of packages.
• We can change the package body with out changing the header.

PACKAGE RUNTIME STATE

• Serially reusable packages
• Non serially reusable packages

SERIALLY REUSABLE PACKAGES

CREATE OR REPLACE PACKAGE PKG IS
pragma serially_reusable;
procedure emp_proc;
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
pragma serially_reusable;
cursor c is select ename from emp;
PROCEDURE EMP_PROC IS
v_ename emp.ename%type;
v_flag boolean := true;
v_numrows number := 0;
BEGIN
if not c%isopen then
   open c;
end if;
while v_flag loop
               fetch c into v_ename;
               v_numrows := v_numrows + 1;
               if v_numrows = 5 then
                  v_flag := false;
               end if;
               dbms_output.put_line('Ename = ' || v_ename);
     end loop;
END EMP_PROC;
END PKG;

SQL> exec pkg.emp_proc
Ename = SMITH
Ename = ALLEN
Ename = WARD
Ename = JONES
Ename = MARTIN


SQL> exec pkg.emp_proc
Ename = SMITH
Ename = ALLEN
Ename = WARD
Ename = JONES
Ename = MARTIN

• The above package displays the same output for each execution even though the cursor is not closed.
• Because the serially reusable version resets the state of the cursor each time it was called.

NON SERIALL Y REUSABLE PACKAGES

CREATE OR REPLACE PACKAGE PKG IS
procedure emp_proc;
END PKG;

CREATE OR REPLACE PACKAGE BODY IS
cursor c is select ename from emp;
PROCEDURE EMP_PROC IS
v_ename emp.ename%type;
v_flag boolean := true;
v_numrows number := 0;
BEGIN
if not c%isopen then
         open c;
    end if;
    while v_flag loop
              fetch c into v_ename;
              v_numrows := v_numrows + 1;
              if v_numrows = 5 then
                 v_flag := false;
              end if;
              dbms_output.put_line('Ename = ' || v_ename);
          end loop;
END EMP_PROC;
END PKG;

SQL> exec pkg.emp_proc
Ename = SMITH
Ename = ALLEN
Ename = WARD
Ename = JONES
Ename = MARTIN

SQL> exec pkg.emp_proc

Ename = BLAKE
Ename = CLARK
Ename = SCOTT
Ename = KING
Ename = TURNER

• The above package displays the different output for each execution even though the cursor is not closed.
• Because the non-serially reusable version remains the state of the cursor over database calls.

DEPENDENCIES OF PACKAGE RUNTIME STATE

Create this package in first session
CREATE OR REPLACE PACKAGE PKG IS
v number := 5;
procedure p;
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
PROCEDURE P IS
BEGIN
dbms_output.put_line('v = ' || v);
v := 10;
dbms_output.put_line('v = ' || v);
END P;
END PKG;

BEGIN
pkg.p;
END;

BEGIN
pkg.p;
 END;

• The anonymous block depends on pkg. This is compile time dependency.
• There is also a runtime dependency on the packaged variables, since each session has its own copy of packaged variables.
• Thus when pkg is recompiled the runtime dependency is followed, which invalidates the block and raises the oracle error.
• Runtime dependencies exist only on package state. This includes variables and cursors declared in a package.
• If the package had no global variables, the second execution of the anonymous block would have succeeded.

PURITY LEVELS

• The function has to be stored in the database, either stand-alone or as part of a package.
• The function can take only in parametes.
• The formal parameters must use only database types, not PL/SQL types such as boolean or record.
• The return type of the function must also be a database type.
• The function must not end the current transaction with commit or rollback, or rollback to a savepoint prior to the function execution.
• It also must not issue any alter session or alter system commands.

RESTRICT_REFERENCES

CREATE OR REPLACE PACKAGE PKG IS
function fun1 return varchar;
pragma restrict_references(fun1,wnds);
function fun2 return varchar;
pragma restrict_references(fun2,wnds);
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
FUNCTION FUN1 return varchar IS
BEGIN
      update dept set deptno = 11;
                 return 'hello';
             END FUN1;
           FUNCTION FUN2 return varchar IS
           BEGIN
                 update dept set dname ='aa';
                 return 'hello';
           END FUN2;
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
FUNCTION FUN1 return varchar IS
BEGIN
                 return 'hello';
             END FUN1;
           FUNCTION FUN2 return varchar IS
           BEGIN
                 return 'hello';
           END FUN2;
END PKG;

DEFAULT

• If there is no RESTRICT_REFERENCES pragma associated with a given packaged function, it will not have any purity level asserted.
• However, you can change the default purity level for a package.
• The DEFAULT keyword is used instead of the subprogram name in the pragma.

CREATE OR REPLACE PACKAGE PKG IS
pragma restrict_references(default,wnds);
function fun1 return varchar;
function fun2 return varchar;
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
FUNCTION FUN1 return varchar IS
BEGIN
      update dept set deptno = 11;
                 return 'hello';
             END FUN1;
           FUNCTION FUN2 return varchar IS
           BEGIN
                 update dept set dname ='aa';
                 return 'hello';
           END FUN2;
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
FUNCTION FUN1 return varchar IS
BEGIN
                 return 'hello';
             END FUN1;
           FUNCTION FUN2 return varchar IS
           BEGIN
                 return 'hello';
           END FUN2;
END PKG;

TRUST

CREATE OR REPLACE PACKAGE PKG IS
function fun1 return varchar;
pragma restrict_references(fun1,wnds,trust);
function fun2 return varchar;
pragma restrict_references(fun2,wnds,trust);
END PKG;

CREATE OR REPLACE PACKAGE BODY PKG IS
FUNCTION FUN1 return varchar IS
BEGIN
      update dept set deptno = 11;
                 return 'hello';
             END FUN1;
           FUNCTION FUN2 return varchar IS
           BEGIN
                 update dept set dname ='aa';
                 return 'hello';
           END FUN2;
END PKG;

IMPORTANT POINTS ABOUT RESTRICT_REFERENCES

• This pragma can appear anywhere in the package specification, after the function declaration.
• It can apply to only one function definition.
• For overload functions, the pragma applies to the nearest definition prior to the pragma.
• This pragma is required only for packages functions not for stand-alone functions.
• The Pragma can be declared only inside the package specification.
• The pragma is checked at compile time, not runtime.
• It is possible to specify without any purity levels when trust or combination of default and trust keywords are present.

PINNING IN THE SHARED POOL

• KEEP
• UNKEEP
• SIZES
• ABORTED_REQUEST_THRESHOLD

KEEP

UNKEEP

SIZES

ABORTED_REQUEST_THRESHOLD

DATA MODEL FOR SUBPROGRAMS AND PACKAGES

• USER_OBJECTS
• USER_SOURCE
• USER_ERRORS
• DBA_OBJECTS
• DBA_SOURCE
• DBA_ERRORS
• ALL_OBJECTS
• ALL_SOURCE
• ALL_ERRORS

CURSORS

• Header
• Body

CURSOR TYPES

• Implicit (SQL)
• Explicit
  • Parameterized cursors
  • REF cursors

CURSOR STAGES

• Open
• Fetch
• Close

CURSOR ATTRIBUTES

• %found
• %notfound
• %rowcount
• %isopen
• %bulk_rowcount
• %bulk_exceptions

CURSOR DECLERATION

CURSOR LOOPS

• Simple loop
• While loop
• For loop

SIMPLE LOOP

	Loop
	       Fetch <cursor_name> into <record_variable>;
	       Exit when <cursor_name> % notfound;
                  <statements>;
	End loop;

DECLARE
     cursor c is select * from student;
     v_stud student%rowtype;
BEGIN
     open c;
     loop
        fetch c into v_stud;
        exit when c%notfound;
        dbms_output.put_line('Name = ' || v_stud.name);
     end loop;
     close c;
END;

Output:
Name = saketh
Name = srinu
Name = satish
Name = sudha

WHILE LOOP

	While <cursor_name> % found loop
	       Fetch <cursor_name> nto <record_variable>;
                  <statements>;
	End loop;

DECLARE
     cursor c is select * from student;
     v_stud student%rowtype;
BEGIN
     open c;
     fetch c into v_stud;
     while c%found loop
          fetch c into v_stud;
          dbms_output.put_line('Name = ' || v_stud.name);
     end loop;
     close c;
END;
Output:
Name = saketh
Name = srinu
Name = satish
Name = sudha

FOR  LOOP

	for <record_variable> in <cursor_name> loop
                  <statements>;
	End loop;

DECLARE
     cursor c is select * from student;
BEGIN
     for v_stud in c loop
         dbms_output.put_line('Name = ' || v_stud.name);
     end loop;
END;

Output:
Name = saketh
Name = srinu
Name = satish
Name = sudha

PARAMETARIZED  CURSORS

• This was used when you are going to use the cursor in more than one place with different values for the same where clause.
• Cursor parameters must be in mode.
• Cursor parameters may have default values.
• The scope of cursor parameter is within the select statement.

 
     DECLARE 
         cursor c(dno in number) is select * from dept where deptno = dno; 
         v_dept dept%rowtype; 
      BEGIN 
         open c(20); 
         loop 
             fetch c into v_dept; 
             exit when c%notfound; 
            dbms_output.put_line('Dname = ' || v_dept.dname || 
                                     ' Loc = ' || v_dept.loc); 
         end loop; 
         close c; 
     END; 
 
Output: 
     Dname = RESEARCH Loc = DALLAS 

PACKAGED CURSORS WITH HEADER IN SPEC AND BODY IN PACKAGE BODY

• cursors declared in packages will not close automatically.
• In packaged cursors you can modify the select statement without making any changes to the cursor header in the package specification.
• Packaged cursors with must be defined in the package body itself, and then use it as global for the package.
• You can not define the packaged cursor in any subprograms.
• Cursor declaration in package with out body needs the return clause.

  
CREATE OR REPLACE PACKAGE PKG IS  
    cursor c return dept%rowtype is select * from dept;
 procedure proc is  
END PKG;  

  
CREATE OR REPLACE PAKCAGE BODY PKG IS  
      cursor c return dept%rowtype is select * from dept;  
PROCEDURE PROC IS  
BEGIN  
      for v in c loop  
     dbms_output.put_line('Deptno = ' || v.deptno || ' Dname = ' || 
                               v.dname || 'Loc = ' || v.loc);  
      end loop;  
END PROC;  
END PKG;  
  
Output:  
SQL> exec pkg.proc  
        Deptno = 10 Dname = ACCOUNTING  Loc = NEW YORK  
        Deptno = 20 Dname = RESEARCH    Loc = DALLAS  
        Deptno = 30 Dname = SALES       Loc = CHICAGO  
        Deptno = 40 Dname = OPERATIONS  Loc = BOSTON  
                    

               
CREATE OR REPLACE PAKCAGE BODY PKG IS  
  cursor c return dept%rowtype is select * from dept where deptno > 20;  
PROCEDURE PROC IS  
BEGIN  
      for v in c loop  
      dbms_output.put_line('Deptno = ' || v.deptno || ' Dname = ' || 
                             v.dname || ' Loc = ' || v.loc);  
      end loop;  
END PROC;  
END PKG;  
  
Output:  
             SQL> exec pkg.proc  
        Deptno = 30 Dname = SALES Loc = CHICAGO  
                  Deptno = 40 Dname = OPERATIONS Loc = BOSTON  

REF CURSORS AND CURSOR VARIABLES

• This is unconstrained cursor which will return different types depends upon the user input.
• Ref cursors can not be closed implicitly.
• Ref cursor with return type is called strong cursor.
• Ref cursor with out return type is called weak cursor.
• You can declare ref cursor type in package spec as well as body.
• You can declare ref cursor types in local subprograms or anonymous blocks.
• Cursor variables can be assigned from one to another.
• You can declare a cursor variable in one scope and assign another cursor variable with different scope, then you can use the cursor variable even though the assigned cursor variable goes out of scope.
• Cursor variables can be passed as a parameters to the subprograms.
• Cursor variables modes are in or out or in out.
• Cursor variables can not be declared in package spec and package body (excluding subprograms).
• You can not user remote procedure calls to pass cursor variables from one server to another.
• Cursor variables can not use for update clause.
• You can not assign nulls to cursor variables.
• You can not compare cursor variables for equality, inequality and nullity.

  
 CREATE OR REPLACE PROCEDURE REF_CURSOR(TABLE_NAME IN VARCHAR) IS
 type t is ref cursor;
 c t;
 v_dept dept%rowtype; 
         type r is record(ename emp.ename%type,job emp.job%type,
                                                sal emp.sal%type); 
         v_emp r; 
         v_stud student.name%type; 
    BEGIN 
         if table_name = 'DEPT' then 
            open c for select * from dept; 
         elsif table_name = 'EMP' then  
            open c for select ename,job,sal from emp; 
         elsif table_name = 'STUDENT' then 
            open c for select name from student; 
         end if; 
         loop 
            if table_name = 'DEPT' then 
               fetch c into v_dept; 
               exit when c%notfound; 
               dbms_output.put_line('Deptno = ' || v_dept.deptno ||
       ' Dname = ' ||  v_dept.dname   || ' Loc = ' || v_dept.loc); 
            elsif table_name = 'EMP' then 
                fetch c into v_emp; 
                exit when c%notfound; 
               dbms_output.put_line('Ename = ' || v_emp.ename || 
                       ' Job = ' || v_emp.job || ' Sal = ' || v_emp.sal); 
            elsif table_name = 'STUDENT' then 
                 fetch c into v_stud; 
                 exit when c%notfound; 
                 dbms_output.put_line('Name = ' || v_stud); 
            end if; 
         end loop;  
         close c;   
    END; 
  
Output:  
SQL> exec ref_cursor('DEPT')  
  
Deptno = 10 Dname = ACCOUNTING Loc = NEW YORK  
Deptno = 20 Dname = RESEARCH Loc = DALLAS  
Deptno = 30 Dname = SALES Loc = CHICAGO  
Deptno = 40 Dname = OPERATIONS Loc = BOSTON  
  
SQL> exec ref_cursor('EMP')  
  
Ename = SMITH Job = CLERK Sal = 800  
Ename = ALLEN Job = SALESMAN Sal = 1600  
Ename = WARD Job = SALESMAN Sal = 1250  
Ename = JONES Job = MANAGER Sal = 2975  
Ename = MARTIN Job = SALESMAN Sal = 1250  
Ename = BLAKE Job = MANAGER Sal = 2850  
Ename = CLARK Job = MANAGER Sal = 2450  
Ename = SCOTT Job = ANALYST Sal = 3000  
Ename = KING Job = PRESIDENT Sal = 5000  
Ename = TURNER Job = SALESMAN Sal = 1500  
Ename = ADAMS Job = CLERK Sal = 1100  
Ename = JAMES Job = CLERK Sal = 950  
Ename = FORD Job = ANALYST Sal = 3000  
Ename = MILLER Job = CLERK Sal = 1300  
  
SQL> exec ref_cursor('STUDENT')  
  
Name = saketh  
Name = srinu  
Name = satish  
Name = sudha

CURSOR EXPRESSIONS

• You can use cursor expressions in explicit cursors.
• You can use cursor expressions in dynamic SQL.
• You can use cursor expressions in REF cursor declarations and variables.
• You can not use cursor expressions in implicit cursors.
• Oracle opens the nested cursor defined by a cursor expression implicitly as soon as it fetches the data containing the cursor expression from the parent or outer cursor.
• Nested cursor closes if you close explicitly.
• Nested cursor closes whenever the outer or parent cursor is executed again or closed or canceled.
• Nested cursor closes whenever an exception is raised while fetching data from a parent cursor.
• Cursor expressions can not be used when declaring a view.
• Cursor expressions can be used as an argument to table function.
• You can not perform bind and execute operations on cursor expressions when using the cursor expressions in dynamic SQL.

USING NESTED CURSORS OR CURSOR EXPRESSIONS

 
DECLARE 
cursor c is select ename,cursor(select dname from dept d 
                            where e.empno = d.deptno) from emp e; 
type t is ref cursor; 
c1 t; 
c2 t; 
v1 emp.ename%type; 
v2 dept.dname%type; 
BEGIN 
open c; 
loop 
     fetch c1 into v1; 
          exit when c1%notfound; 
          fetch c2 into v2; 
          exit when c2%notfound; 
          dbms_output.put_line('Ename = ' || v1 || ' Dname = ' || v2); 
end loop; 
end loop; 
close c; 
END; 

CURSOR CLAUSES

• Return
• For update
• Where current of
• Bulk collect

RETURN

FOR UPDATE AND WHERE CURRENT OF

DECLARE
       cursor c is select * from dept for update of dname;
BEGIN
       for v in c loop
             update dept set dname = 'aa' where current of c;
             commit;
       end loop;
END;

BULK COLLECT

• This is used for array fetches
• With this you can retrieve multiple rows of data with a single roundtrip.
• This reduces the number of context switches between the pl/sql and sql engines.
• Reduces the overhead of retrieving data.
• You can use bulk collect in both dynamic and static sql.
• You can use bulk collect in select, fetch into and returning into clauses.
• SQL engine automatically initializes and extends the collections you reference in the bulk collect clause.
• Bulk collect operation empties the collection referenced in the into clause before executing the query.
• You can use the limit clause of bulk collect to restrict the no of rows retrieved.
• You can fetch into multible collections with one column each.
• Using the returning clause we can return data to the another collection.

BULK COLLECT IN FETCH

  
DECLARE  
     Type t is table of dept%rowtype;  
     nt t;  
     Cursor c is select *from dept;  
BEGIN  
     Open c;  
     Fetch c bulk collect into nt;  
     Close c;  
     For i in nt.first..nt.last loop  
     dbms_output.put_line('Dname = ' || nt(i).dname || ' Loc = ' || nt(i).loc); 
     end loop;  
END;  
Output:  
Dname = ACCOUNTING Loc = NEW YORK  
Dname = RESEARCH Loc = DALLAS  
Dname = SALES Loc = CHICAGO  
Dname = OPERATIONS Loc = BOSTON  

BULK  COLLECT  IN  SELECT

  
DECLARE  
     Type t is table of dept%rowtype;  
     Nt t;  
BEGIN  
     Select * bulk collect into nt from dept;  
     for i in nt.first..nt.last loop  
     dbms_output.put_line('Dname = ' || nt(i).dname || ' Loc = ' || nt(i).loc);
     end loop;  
END;  
  
Output:  
Dname = ACCOUNTING Loc = NEW YORK  
Dname = RESEARCH Loc = DALLAS  
Dname = SALES Loc = CHICAGO  
Dname = OPERATIONS Loc = BOSTON  

LIMIT IN BULK COLLECT

  
DECLARE  
     Type t is table of dept%rowtype;  
     nt t;  
     Cursor c is select *from dept;  
BEGIN  
     Open c;  
     Fetch c bulk collect into nt limit 2;  
     Close c;  
     For i in nt.first..nt.last loop  
     dbms_output.put_line('Dname = ' || nt(i).dname || ' Loc = ' || nt(i).loc);
end loop;  
END;  
  
Output:  
Dname = ACCOUNTING Loc = NEW YORK  
Dname = RESEARCH Loc = DALLAS  

MULTIPLE FETCHES IN INTO CLAUSE

     DECLARE
           Type t is table of dept.dname%type;
           nt t;
           Type t1 is table of dept.loc%type;
           nt1 t;
           Cursor c is select dname,loc from dept;
      BEGIN
           Open c;
           Fetch c bulk collect into nt,nt1;
           Close c;
           For i in nt.first..nt.last loop
                  dbms_output.put_line('Dname = ' || nt(i));
           end loop;
           For i in nt1.first..nt1.last loop
                  dbms_output.put_line('Loc = ' || nt1(i));
           end loop;
      END;

Output:
Dname = ACCOUNTING
Dname = RESEARCH
Dname = SALES
Dname = OPERATIONS
Loc = NEW YORK
Loc = DALLAS
Loc = CHICAGO
Loc = BOSTON

DECLARE
      type t is table of dept.dname%type;
      type t1 is table of dept.loc%type;
      nt t;
      nt1 t1;
BEGIN
      Select dname,loc bulk collect into nt,nt1 from dept;
      for i in nt.first..nt.last loop
           dbms_output.put_line('Dname = ' || nt(i));
      end loop;
      for i in nt1.first..nt1.last loop
           dbms_output.put_line('Loc = ' || nt1(i));
      end loop;
END;

Output:
Dname = ACCOUNTING
Dname = RESEARCH
Dname = SALES
Dname = OPERATIONS
Loc = NEW YORK
Loc = DALLAS
Loc = CHICAGO
Loc = BOSTON

RETURNING CLAUSE IN BULK COLLECT

  
DECLARE  
       type t is table of number(2);  
       nt t := t(1,2,3,4);  
       type t1 is table of varchar(2);  
       nt1 t1;  
       type t2 is table of student%rowtype;  
       nt2 t2;  
BEGIN  
       select name bulk collect into nt1 from student;  
       forall v in nt1.first..nt1.last  
          update student set no = nt(v) where name = nt1(v) returning
                                 no,name,marks bulk collect into nt2;  
       for v in nt2.first..nt2.last loop  
               dbms_output.put_line('Marks = ' || nt2(v));  
       end loop;  
END;  
  
Output:  
Marks = 100  
Marks = 200  
Marks = 300  
Marks = 400  

POINTS TO REMEMBER

• Cursor name can be up to 30 characters in length.
• Cursors declared in anonymous blocks or subprograms closes automatically when that block terminates execution.
• %bulk_rowcount and %bulk_exceptions can be used only with forall construct.
• Cursor declarations may have expressions with column aliases.
• These expressions are called virtual columns or calculated columns.

SQL IN PL/SQL

BINDING

• Early binding
• Late binding

• Binding during the compiled phase is early binding.
• Binding during the runtime phase is late binding.
• In early binding compile phase will take longer because of binding work but the execution is faster.
• In late binding it will shorten the compile phase but lengthens the execution time.
• PL/SQL by default uses early binding.
• Binding also involves checking the database for permissions to access the object Referenced.

DYNAMIC SQL

• If you use DDL in pl/sql it validates the permissions and existence if requires during compile time which makes invalid.
• We can avoid this by using Dynamic SQL.
• Dynamic SQL allows you to create a SQL statement dynamically at runtime.

• Native Dynamic SQL
• DBMS_SQL package

USING NATIVE DYNAMIC SQL

USING EXECUTE IMMEDIATE

 
BEGIN 
      Execute immediate 'create table student(no number(2),name varchar(10))'; 
or 
      Execute immediate ('create table student(no number(2),name varchar(10))'); 
END; 

USING EXECUTE IMMEDIATE WITH PL/SQL VARIABLES

DECLARE
      v varchar(100);
BEGIN
      v := 'create table student(no number(2),name varchar(10))';
      execute immediate v;
END;

USING EXECUTE IMMEDIATE WITH BIND VARIABLES AND USING CLAUSE

DECLARE
      v varchar(100);
BEGIN
      v := 'insert into student values(:v1,:v2,:v3)';
      execute immediate v using 6,'f',600;
END;

EXECUTING QUERIES WITH OPEN FOR AND USING CLAUSE

CREATE OR REPLACE PROCEDURE P(smarks in number) IS
      s varchar(100) := 'select *from student where marks > :m';
      type t is ref cursor;
      c t;
      v student%rowtype;
BEGIN
      open c for s using smarks;
      loop
           fetch c into v;
           exit when c%notfound;
           dbms_output.put_line('Student Marks = ' || v.marks);
      end loop;
      close c;
END;
   
Output:
	SQL> exec p(100)

        Student Marks = 200
                   Student Marks = 300
                   Student Marks = 400

QUERIES WITH EXECUTE IMMEDIATE

   DECLARE
        d_name dept.dname%type;
        lc dept.loc%type;
        v varchar(100);
   BEGIN
        v := 'select dname from dept where deptno = 10';
        execute immediate v into d_name;
        dbms_output.put_line('Dname = '|| d_name);
        v := 'select loc from dept where dname = :dn';
        execute immediate v into lc using d_name;
        dbms_output.put_line('Loc = ' || lc);
   END;

Output:
Dname = ACCOUNTING
Loc = NEW YORK
VARIABLE NAMES

 
DECLARE 
     Marks number(3) := 100; 
BEGIN 
     Delete student where marks = marks;     -- this will delete all the rows
                                                      in the student table  
END;  

  
  
<<my_block>>  
DECLARE  
     Marks number(3) := 100;  
BEGIN  
     Delete student where marks = my_block.marks;   -- delete rows which has a  
                                                           marks of 100  
END;  

GETTING DATA INTO PL/SQL VARIABLES

DECLARE
     V1 number;
     V2 varchar(2);
BEGIN
     Select no,name into v1,v2 from student where marks = 100;
END;

DML AND RECORDS

CREATE OR REPLACE PROCEDURE P(srow in student%rowtype) IS
BEGIN
insert into student values srow;
END P;

DECLARE
     s student%rowtype;
BEGIN
     s.no := 11;
     s.name := 'aa';
     s.marks := 100;
     p(s);
END;

RECORD BASED INSERTS

DECLARE
     srow student%rowtype;
BEGIN
     srow.no := 7;
     srow.name := 'cc';
     srow.marks := 500;
     insert into student values srow;
END;

RECORD BASED UPDATES

DECLARE
      srow student%rowtype;
BEGIN
      srow.no := 6;
      srow.name := 'cc';
      srow.marks := 500;
      update student set row=srow where no = srow.no;
END;

USING RECORDS WITH RETURNING CLAUSE

DECLARE
      srow student%rowtype;
      sreturn student%rowtype;
BEGIN
      srow.no := 8;
      srow.name := 'dd';
      srow.marks := 500;
      insert into student values srow returning no,name,marks into sreturn;
      dbms_output.put_line('No = ' || sreturn.no);
      dbms_output.put_line('No = ' || sreturn.name);
      dbms_output.put_line('No = ' || sreturn.marks);
END;

Output:
No = 8
No = dd
No = 500

FORALL STATEMENT

	Forall index_var in
	          [ Lower_bound..upper_bound |
		Indices of indexing_collection |
		Values of indexing_collection ]
        SQL statement;

FORALL WITH NON-SEQUENTIAL ARRAYS

DECLARE
     type t is table of student.no%type index by binary_integer;
     ibt t;
BEGIN
     ibt(1) := 1; 
     ibt(10) := 2;
     forall i in ibt.first..ibt.last
              update student set marks = 900 where no = ibt(i);
END;

USGAGE OF INDICES OF TO AVOID THE ABOVE BEHAVIOUR

DECLARE
      type t is table of student.no%type index by binary_integer;
      ibt t;
      type t1 is table of boolean index by binary_integer;
      ibt1 t1;
BEGIN
      ibt(1) := 1;
      ibt(10) := 2;
      ibt(100) := 3;
      ibt1(1) := true;
      ibt1(10) := true;
      ibt1(100) := true;
      forall i in indices of ibt1
                update student set marks = 900 where no = ibt(i);
END;

USGAGE OF INDICES OF TO AVOID THE ABOVE BEHAVIOUR

 DECLARE
      type t is table of student.no%type index by binary_integer;
      ibt t;
      type t1 is table of pls_integer index by binary_integer;
      ibt1 t1;
 BEGIN
      ibt(1) := 1;
      ibt(10) := 2;
      ibt(100) := 3;
      ibt1(11) := 1;
      ibt1(15) := 10;
      ibt1(18) := 100;
      forall i in values of ibt1
                update student set marks = 567 where no = ibt(i);
END;

POINTS ABOUT BULK BINDS

• Passing the entire PL/SQL table to the SQL engine in one step is known as bulk bind.
• Bulk binds are done using the forall statement.
• If there is an error processing one of the rows in bulk DML operation, only that row is rolled back.

POINTS ABOUT RETURING CLAUSE

• This will be used only with DML statements to return data into PL/SQL variables.
• This will be useful in situations like , when performing insert or update or delete if you want to know the data of the table which has been effected by the DML.
• With out going for another SELECT using RETURNING clause we will get the data which will avoid a call to RDBMS kernel.

COLLECTIONS

• Collections are also composite types, in that they allow you to treat several variables as a unit.
• A collection combines variables of the same type.

TYPES

• Varrays
• Nested tables
• Index - by tables (Associate arrays)

VARRAYS

• A varray is datatype very similar to an array.
• A varray has a fixed limit on its size, specified as part of the declaration.
• Elements are inserted into varray starting at index 1, up to maximum lenth declared in the varray type.
• The maximum size of the varray is 2 giga bytes.

 
DECLARE 
      type t is varray(10) of varchar(2); 
      va t := t('a','b','c','d'); 
      flag boolean; 
BEGIN 
      dbms_output.put_line('Limit = ' || va.limit); 
      dbms_output.put_line('Count = ' || va.count); 
      dbms_output.put_line('First Index = ' || va.first); 
      dbms_output.put_line('Last Index = ' || va.last); 
      dbms_output.put_line('Next Index = ' || va.next(2)); 
      dbms_output.put_line('Previous Index = ' || va.prior(3)); 
      dbms_output.put_line('VARRAY ELEMENTS'); 
      for i in va.first..va.last loop 
            dbms_output.put_line('va[' || i || '] = ' || va(i)); 
      end loop; 
      flag := va.exists(3); 
      if flag = true then 
          dbms_output.put_line('Index 3 exists with an element ' || va(3)); 
      else 
          dbms_output.put_line('Index 3 does not exists'); 
      end if; 
      va.extend; 
      dbms_output.put_line('After extend of one index, Count = ' || va.count); 
      flag := va.exists(5); 
      if flag = true then 
          dbms_output.put_line('Index 5 exists with an element ' || va(5)); 
      else 
          dbms_output.put_line('Index 5 does not exists'); 
      end if; 
      flag := va.exists(6); 
      if flag = true then 
          dbms_output.put_line('Index 6 exists with an element ' || va(6)); 
      else 
          dbms_output.put_line('Index 6 does not exists'); 
      end if; 
      va.extend(2); 
      dbms_output.put_line('After extend of two indexes, Count = ' || va.count); 
      dbms_output.put_line('VARRAY ELEMENTS'); 
      for i in va.first..va.last loop 
            dbms_output.put_line('va[' || i || '] = ' || va(i)); 
      end loop; 
      va(5) := 'e'; 
      va(6) := 'f'; 
      va(7) := 'g'; 
      dbms_output.put_line('AFTER ASSINGNING VALUES TO EXTENDED ELEMENTS,     
                                                        VARRAY ELEMENTS'); 
      for i in va.first..va.last loop 
            dbms_output.put_line('va[' || i || '] = ' || va(i)); 
      end loop; 
      va.extend(3,2); 
      dbms_output.put_line('After extend of three indexes, 
                                               Count = ' || va.count); 
      dbms_output.put_line('VARRAY ELEMENTS'); 
      for i in va.first..va.last loop 
            dbms_output.put_line('va[' || i || '] = ' || va(i)); 
      end loop; 
      va.trim; 
      dbms_output.put_line('After trim of one index, Count = ' || va.count); 
      va.trim(3); 
      dbms_output.put_line('After trim of three indexs, Count = ' || va.count); 
      dbms_output.put_line('AFTER TRIM, VARRAY ELEMENTS'); 
      for i in va.first..va.last loop 
            dbms_output.put_line('va[' || i || '] = ' || va(i)); 
      end loop; 
      va.delete; 
      dbms_output.put_line('After delete of entire varray, 
                                      Count = ' || va.count); 
END; 
 
Output: 
Limit = 10 
Count = 4 
First Index = 1 
Last Index = 4 
Next Index = 3 
Previous Index = 2 
VARRAY ELEMENTS 
va[1] = a 
va[2] = b 
va[3] = c 
va[4] = d 
Index 3 exists with an element c 
After extend of one index, Count = 5 
Index 5 exists with an element 
Index 6 does not exists 
After extend of two indexes, Count = 7 
VARRAY ELEMENTS 
va[1] = a 
va[2] = b 
va[3] = c 
va[4] = d 
va[5] = 
va[6] = 
va[7] = 
AFTER ASSINGNING VALUES TO EXTENDED ELEMENTS, VARRAY ELEMENTS 
va[1] = a 
va[2] = b 
va[3] = c 
va[4] = d 
va[5] = e 
va[6] = f 
va[7] = g 
After extend of three indexes, Count = 10 
VARRAY ELEMENTS 
va[1] = a 
va[2] = b 
va[3] = c 
va[4] = d 
va[5] = e 
va[6] = f 
va[7] = g 
va[8] = b 
va[9] = b 
va[10] = b 
After trim of one index, Count = 9 
After trim of three indexs, Count = 6 
AFTER TRIM, VARRAY ELEMENTS 
va[1] = a 
va[2] = b 
va[3] = c 
va[4] = d 
va[5] = e 
va[6] = f 
After delete of entire varray, Count = 0 

 
DECLARE 
      type t is varray(4) of student%rowtype; 
      va t := t(null,null,null,null); 
BEGIN 
      for i in 1..va.count loop 
       select * into va(i) from student where sno = i; 
       dbms_output.put_line('Sno = ' || va(i).sno || ' Sname = ' || va(i).sname); 
      end loop; 
END; 
 
Output: 
Sno = 1 Sname = saketh 
Sno = 2 Sname = srinu 
Sno = 3 Sname = divya 
Sno = 4 Sname = manogni 

DECLARE
       type t is varray(4) of student.smarks%type;
       va t := t(null,null,null,null);
BEGIN
       for i in 1..va.count loop
             select smarks into va(i) from student where sno = i;
             dbms_output.put_line('Smarks = ' || va(i));
       end loop;
END;

Output:
Smarks = 100
Smarks = 200
Smarks = 300
Smarks = 400

 
DECLARE 
       type r is record(c1 student.sname%type,c2 student.smarks%type); 
       type t is varray(4) of r; 
       va t := t(null,null,null,null); 
BEGIN 
       for i in 1..va.count loop 
         select sname,smarks into va(i) from student where sno = i; 
         dbms_output.put_line('Sname = ' || va(i).c1 || ' Smarks = ' 
                                                        || va(i).c2); 
       end loop; 
END; 
 
Output: 
Sname = saketh Smarks = 100 
Sname = srinu Smarks = 200 
Sname = divya Smarks = 300 
Sname = manogni Smarks = 400 

 
DECLARE 
        type t is varray(1) of addr; 
        va t := t(null); 
        cursor c is select * from employ; 
        i number := 1; 
BEGIN 
        for v in c loop 
         select address into va(i) from employ where ename = v.ename; 
         dbms_output.put_line('Hno = ' || va(i).hno || ' City = ' 
                                                     || va(i).city); 
        end loop; 
END; 
 
Output: 
Hno = 11 City = hyd 
Hno = 22 City = bang 
Hno = 33 City = kochi 

DECLARE
       type t is varray(5) of varchar(2);
       va1 t;
       va2 t := t();
BEGIN
       if va1 is null then
          dbms_output.put_line('va1 is null');
       else
          dbms_output.put_line('va1 is not null');
       end if;
       if va2 is null then
          dbms_output.put_line('va2 is null');
       else
          dbms_output.put_line('va2 is not null');
       end if;
END;

Output:
va1 is null
va2 is not null

NESTED TABLES

• A nested table is thought of a database table which has no limit on its size.
• Elements are inserted into nested table starting at index 1.
• The maximum size of the varray is 2 giga bytes.

 
DECLARE 
       type t is table of varchar(2); 
       nt t := t('a','b','c','d'); 
       flag boolean; 
BEGIN 
       if nt.limit is null then 
           dbms_output.put_line('No limit to Nested Tables'); 
       else 
           dbms_output.put_line('Limit = ' || nt.limit); 
       end if; 
       dbms_output.put_line('Count = ' || nt.count); 
       dbms_output.put_line('First Index = ' || nt.first); 
       dbms_output.put_line('Last Index = ' || nt.last); 
       dbms_output.put_line('Next Index = ' || nt.next(2)); 
       dbms_output.put_line('Previous Index = ' || nt.prior(3)); 
       dbms_output.put_line('NESTED TABLE ELEMENTS'); 
       for i in 1..nt.count loop 
             dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       flag := nt.exists(3); 
       if flag = true then 
          dbms_output.put_line('Index 3 exists with an element ' || nt(3)); 
       else 
            dbms_output.put_line('Index 3 does not exists'); 
       end if; 
       nt.extend; 
       dbms_output.put_line('After extend of one index, Count = ' || nt.count); 
       flag := nt.exists(5); 
       if flag = true then 
           dbms_output.put_line('Index 5 exists with an element ' || nt(5)); 
       else 
           dbms_output.put_line('Index 5 does not exists'); 
       end if; 
       flag := nt.exists(6); 
       if flag = true then 
           dbms_output.put_line('Index 6 exists with an element ' || nt(6)); 
       else 
           dbms_output.put_line('Index 6 does not exists'); 
       end if; 
       nt.extend(2); 
       dbms_output.put_line('After extend of two indexes, Count = ' || nt.count); 
       dbms_output.put_line('NESTED TABLE ELEMENTS'); 
       for i in 1..nt.count loop 
            dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt(5) := 'e'; 
       nt(6) := 'f'; 
       nt(7) := 'g'; 
       dbms_output.put_line('AFTER ASSINGNING VALUES TO EXTENDED ELEMENTS,
                                                  NESTED TABLE ELEMENTS'); 
       for i in 1..nt.count loop 
              dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt.extend(5,2); 
       dbms_output.put_line('After extend of five indexes, Count = ' || nt.count); 
       dbms_output.put_line('NESTED TABLE ELEMENTS'); 
       for i in 1..nt.count loop 
             dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt.trim; 
       dbms_output.put_line('After trim of one index, Count = ' || nt.count); 
       nt.trim(3); 
       dbms_output.put_line('After trim of three indexs, Count = ' || nt.count); 
       dbms_output.put_line('AFTER TRIM, NESTED TABLE ELEMENTS'); 
       for i in 1..nt.count loop 
               dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt.delete(1); 
       dbms_output.put_line('After delete of first index, Count = ' || nt.count); 
       dbms_output.put_line('NESTED TABLE ELEMENTS'); 
       for i in 2..nt.count+1 loop 
             dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt.delete(4); 
       dbms_output.put_line('After delete of fourth index, Count = ' || nt.count); 
       dbms_output.put_line('NESTED TABLE ELEMENTS'); 
       for i in 2..3 loop 
             dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       for i in 5..nt.count+2 loop 
             dbms_output.put_line('nt[' || i || '] = ' || nt(i)); 
       end loop; 
       nt.delete; 
       dbms_output.put_line('After delete of entire nested table,
                                           Count = ' || nt.count); 
END; 
 
Output: 
No limit to Nested Tables 
Count = 4 
First Index = 1 
Last Index = 4 
Next Index = 3 
Previous Index = 2 
NESTED TABLE ELEMENTS 
nt[1] = a 
nt[2] = b 
nt[3] = c 
nt[4] = d 
Index 3 exists with an element c 
After extend of one index, Count = 5 
Index 5 exists with an element 
Index 6 does not exists 
After extend of two indexes, Count = 7 
NESTED TABLE ELEMENTS 
nt[1] = a 
nt[2] = b 
nt[3] = c 
nt[4] = d 
nt[5] = 
nt[6] = 
nt[7] = 
AFTER ASSINGNING VALUES TO EXTENDED ELEMENTS, NESTED TABLE ELEMENTS 
nt[1] = a 
nt[2] = b 
nt[3] = c 
nt[4] = d 
nt[5] = e 
nt[6] = f 
nt[7] = g 
After extend of five indexes, Count = 12 
NESTED TABLE ELEMENTS 
nt[1] = a 
nt[2] = b 
nt[3] = c 
nt[4] = d 
nt[5] = e 
nt[6] = f 
nt[7] = g 
nt[8] = b 
nt[9] = b 
nt[10] = b 
nt[11] = b 
nt[12] = b 
After trim of one index, Count = 11 
After trim of three indexs, Count = 8 
AFTER TRIM, NESTED TABLE ELEMENTS 
nt[1] = a 
nt[2] = b 
nt[3] = c 
nt[4] = d 
nt[5] = e 
nt[6] = f 
nt[7] = g 
nt[8] = b 
After delete of first index, Count = 7 
NESTED TABLE ELEMENTS 
nt[2] = b 
nt[3] = c 
nt[4] = d 
nt[5] = e 
nt[6] = f 
nt[7] = g 
nt[8] = b 
After delete of fourth index, Count = 6 
NESTED TABLE ELEMENTS 
nt[2] = b 
nt[3] = c 
nt[5] = e 
nt[6] = f 
nt[7] = g 
nt[8] = b 
After delete of entire nested table, Count = 0 

 
DECLARE 
      type t is table of student%rowtype; 
      nt t := t(null,null,null,null); 
BEGIN 
      for i in 1..nt.count loop 
       select * into nt(i) from student where sno = i; 
       dbms_output.put_line('Sno = ' || nt(i).sno || ' Sname = ' || nt(i).sname); 
      end loop; 
END; 
 
Output: 
Sno = 1 Sname = saketh 
Sno = 2 Sname = srinu 
Sno = 3 Sname = divya 
Sno = 4 Sname = manogni 

DECLARE
       type t is table of student.smarks%type;
       nt t := t(null,null,null,null);
BEGIN
       for i in 1..nt.count loop
             select smarks into nt(i) from student where sno = i;
             dbms_output.put_line('Smarks = ' || nt(i));
       end loop;
END;

Output:
Smarks = 100
Smarks = 200
Smarks = 300
Smarks = 400

 
DECLARE 
       type r is record(c1 student.sname%type,c2 student.smarks%type); 
       type t is table of r; 
       nt t := t(null,null,null,null); 
BEGIN 
       for i in 1..nt.count loop 
        select sname,smarks into nt(i) from student where sno = i; 
        dbms_output.put_line('Sname = ' || nt(i).c1 || ' Smarks = ' || nt(i).c2); 
       end loop; 
END; 
 
Output: 
Sname = saketh Smarks = 100 
Sname = srinu Smarks = 200 
Sname = divya Smarks = 300 
Sname = manogni Smarks = 400 

DECLARE
        type t is table of addr;
        nt t := t(null);
        cursor c is select * from employ;
        i number := 1;
BEGIN
        for v in c loop
             select address into nt(i) from employ where ename = v.ename;
             dbms_output.put_line('Hno = ' || nt(i).hno || ' City = ' || nt(i).city);
        end loop;
END;

Output:
Hno = 11 City = hyd
Hno = 22 City = bang
Hno = 33 City = kochi

DECLARE
       type t is varray(5) of varchar(2);
       nt1 t;
       nt2 t := t();
BEGIN
       if nt1 is null then
          dbms_output.put_line('nt1 is null');
       else
          dbms_output.put_line('nt1 is not null');
       end if;
       if nt2 is null then
          dbms_output.put_line('nt2 is null');
       else
          dbms_output.put_line('nt2 is not null');
       end if;
END;

Output:
nt1 is null
nt2 is not null

INDEX-BY TABLES

• An index-by table has no limit on its size.
• Elements are inserted into index-by table whose index may start non-sequentially including negative integers.

 
DECLARE 
       type t is table of varchar(2) index by binary_integer; 
       ibt t; 
       flag boolean; 
BEGIN 
       ibt(1) := 'a'; 
       ibt(-20) := 'b'; 
       ibt(30) := 'c'; 
       ibt(100) := 'd'; 
       if ibt.limit is null then 
          dbms_output.put_line('No limit to Index by Tables'); 
       else 
          dbms_output.put_line('Limit = ' || ibt.limit); 
       end if; 
       dbms_output.put_line('Count = ' || ibt.count); 
       dbms_output.put_line('First Index = ' || ibt.first); 
       dbms_output.put_line('Last Index = ' || ibt.last); 
       dbms_output.put_line('Next Index = ' || ibt.next(2)); 
       dbms_output.put_line('Previous Index = ' || ibt.prior(3)); 
       dbms_output.put_line('INDEX BY TABLE ELEMENTS'); 
       dbms_output.put_line('ibt[-20] = ' || ibt(-20)); 
       dbms_output.put_line('ibt[1] = ' || ibt(1)); 
       dbms_output.put_line('ibt[30] = ' || ibt(30)); 
       dbms_output.put_line('ibt[100] = ' || ibt(100)); 
       flag := ibt.exists(30); 
       if flag = true then 
          dbms_output.put_line('Index 30 exists with an element ' || ibt(30)); 
       else 
          dbms_output.put_line('Index 30 does not exists'); 
       end if; 
       flag := ibt.exists(50); 
       if flag = true then 
          dbms_output.put_line('Index 50 exists with an element ' || ibt(30)); 
       else 
          dbms_output.put_line('Index 50 does not exists'); 
       end if; 
       ibt.delete(1); 
       dbms_output.put_line('After delete of first index, Count = ' || ibt.count); 
       ibt.delete(30); 
       dbms_output.put_line('After delete of index thirty, Count = ' || ibt.count); 
       dbms_output.put_line('INDEX BY TABLE ELEMENTS'); 
       dbms_output.put_line('ibt[-20] = ' || ibt(-20)); 
       dbms_output.put_line('ibt[100] = ' || ibt(100)); 
       ibt.delete; 
       dbms_output.put_line('After delete of entire 
                               index-by table, Count = ' || ibt.count); 
END; 
 
Output: 
No limit to Index by Tables 
Count = 4 
First Index = -20 
Last Index = 100 
Next Index = 30 
Previous Index = 1 
INDEX BY TABLE ELEMENTS 
ibt[-20] = b 
ibt[1] = a 
ibt[30] = c 
ibt[100] = d 
Index 30 exists with an element c 
Index 50 does not exists 
After delete of first index, Count = 3 
After delete of index thirty, Count = 2 
INDEX BY TABLE ELEMENTS 
ibt[-20] = b 
ibt[100] = d 
After delete of entire index-by table, Count = 0 

• Varrays has limit, nested tables and index-by tables has no limit.
• Varrays and nested tables must be initialized before assignment of elements, in index-by tables we can directly assign elements.
• Varrays and nested tables stored in database, but index-by tables can not.
• Nested tables and index-by tables are PL/SQL tables, but varrays can not.
• Keys must be positive in case of nested tables and varrays, in case of index-by tables keys can be positive or negative.
• Referencing nonexistent elements raises SUBSCRIPT_BEYOND_COUNT in both nested tables and varrays, but in case of index-by tables NO_DATA_FOUND raises.
• Keys are sequential in both nested tables and varrays, non-sequential in index-by tables.
• Individual indexes can be deleted in both nested tables and index-by tables, but in varrays can not.
• Individual indexes can be trimmed in both nested tables and varrays, but in index-by tables can not.
• Individual indexes can be extended in both nested tables and varrays, but in index-by tables can not.

MULTILEVEL COLLECTIONS

 
DECLARE 
        type t1 is table of varchar(2) index by binary_integer; 
        type t2 is varray(5) of t1; 
        va t2 := t2(); 
        c number := 97; 
        flag boolean; 
BEGIN 
        va.extend(4); 
        dbms_output.put_line('Count = ' || va.count); 
        dbms_output.put_line('Limit = ' || va.limit); 
        for i in 1..va.count loop 
              for j in 1..va.count loop 
                    va(i)(j) := chr(c); 
                    c := c + 1; 
              end loop; 
        end loop; 
        dbms_output.put_line('VARRAY ELEMENTS'); 
        for i in 1..va.count loop 
          for j in 1..va.count loop 
           dbms_output.put_line('va[' || i || '][' || j || '] = ' || va(i)(j)); 
          end loop; 
        end loop; 
        dbms_output.put_line('First index = ' || va.first); 
        dbms_output.put_line('Last index = ' || va.last); 
        dbms_output.put_line('Next index = ' || va.next(2)); 
        dbms_output.put_line('Previous index = ' || va.prior(3)); 
        flag := va.exists(2); 
        if flag = true then 
            dbms_output.put_line('Index 2 exists'); 
        else 
            dbms_output.put_line('Index 2 exists'); 
        end if; 
        va.extend; 
        va(1)(5) := 'q'; 
        va(2)(5) := 'r'; 
        va(3)(5) := 's'; 
        va(4)(5) := 't'; 
        va(5)(1) := 'u'; 
        va(5)(2) := 'v'; 
        va(5)(3) := 'w'; 
        va(5)(4) := 'x'; 
        va(5)(5) := 'y'; 
        dbms_output.put_line('After extend of one index, Count = ' || va.count); 
        dbms_output.put_line('VARRAY ELEMENTS'); 
        for i in 1..va.count loop 
           for j in 1..va.count loop 
            dbms_output.put_line('va[' || i || '][' || j || '] = ' || va(i)(j)); 
           end loop; 
        end loop; 
        va.trim; 
        dbms_output.put_line('After trim of one index, Count = ' || va.count); 
        va.trim(2); 
        dbms_output.put_line('After trim of two indexes, Count = ' || va.count); 
        dbms_output.put_line('VARRAY ELEMENTS'); 
        for i in 1..va.count loop 
              for j in 1..va.count loop 
               dbms_output.put_line('va[' || i || '][' || j || '] = ' || va(i)(j));
        end loop; 
        end loop; 
        va.delete; 
        dbms_output.put_line('After delete of entire varray, Count = ' || va.count); 
END; 
 
Output: 
Count = 4 
Limit = 5 
VARRAY ELEMENTS 
va[1][1] = a 
va[1][2] = b 
va[1][3] = c 
va[1][4] = d 
va[2][1] = e 
va[2][2] = f 
va[2][3] = g 
va[2][4] = h 
va[3][1] = i 
va[3][2] = j 
va[3][3] = k 
va[3][4] = l 
va[4][1] = m 
va[4][2] = n 
va[4][3] = o 
va[4][4] = p 
First index = 1 
Last index = 4 
Next index = 3 
Previous index = 2 
Index 2 exists 
After extend of one index, Count = 5 
VARRAY ELEMENTS 
va[1][1] = a 
va[1][2] = b 
va[1][3] = c 
va[1][4] = d 
va[1][5] = q 
va[2][1] = e 
va[2][2] = f 
va[2][3] = g 
va[2][4] = h 
va[2][5] = r 
va[3][1] = i 
va[3][2] = j 
va[3][3] = k 
va[3][4] = l 
va[3][5] = s 
va[4][1] = m 
va[4][2] = n 
va[4][3] = o 
va[4][4] = p 
va[4][5] = t 
va[5][1] = u 
va[5][2] = v 
va[5][3] = w 
va[5][4] = x 
va[5][5] = y 
After trim of one index, Count = 4 
After trim of two indexes, Count = 2 
VARRAY ELEMENTS 
va[1][1] = a 
va[1][2] = b 
va[2][1] = e 
va[2][2] = f 
After delete of entire varray, Count = 0 

 
DECLARE 
        type t1 is table of varchar(2) index by binary_integer; 
        type t2 is table of t1; 
        nt t2 := t2(); 
        c number := 65; 
        v number := 1; 
        flag boolean; 
BEGIN 
        nt.extend(4); 
        dbms_output.put_line('Count = ' || nt.count); 
        if nt.limit is null then 
            dbms_output.put_line('No limit to Nested Tables'); 
        else 
            dbms_output.put_line('Limit = ' || nt.limit); 
        end if; 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                    nt(i)(j) := chr(c); 
                    c := c + 1; 
                    if c = 91 then  
                       c := 97; 
                    end if; 
              end loop; 
        end loop; 
        dbms_output.put_line('NESTED TABLE ELEMENTS'); 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                    dbms_output.put_line(
                          'nt[' || i || '][' || j || '] = ' || nt(i)(j)); 
              end loop; 
        end loop; 
        dbms_output.put_line('First index = ' || nt.first); 
        dbms_output.put_line('Last index = ' || nt.last); 
        dbms_output.put_line('Next index = ' || nt.next(2)); 
        dbms_output.put_line('Previous index = ' || nt.prior(3)); 
        flag := nt.exists(2); 
        if flag = true then 
            dbms_output.put_line('Index 2 exists'); 
        else 
            dbms_output.put_line('Index 2 exists'); 
        end if; 
        nt.extend(2); 
        nt(1)(5) := 'Q'; 
        nt(1)(6) := 'R'; 
        nt(2)(5) := 'S'; 
        nt(2)(6) := 'T'; 
        nt(3)(5) := 'U'; 
        nt(3)(6) := 'V'; 
        nt(4)(5) := 'W'; 
        nt(4)(6) := 'X'; 
        nt(5)(1) := 'Y'; 
        nt(5)(2) := 'Z'; 
        nt(5)(3) := 'a'; 
        nt(5)(4) := 'b'; 
        nt(5)(5) := 'c'; 
        nt(5)(6) := 'd'; 
        nt(6)(1) := 'e'; 
        nt(6)(2) := 'f'; 
        nt(6)(3) := 'g'; 
        nt(6)(4) := 'h'; 
        nt(6)(5) := 'i'; 
        nt(6)(6) := 'j'; 
        dbms_output.put_line('After extend of one index, Count = ' || nt.count); 
        dbms_output.put_line('NESTED TABLE ELEMENTS'); 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                    dbms_output.put_line(
                       'nt[' || i || '][' || j || '] = ' || nt(i)(j)); 
              end loop; 
        end loop; 
        nt.trim; 
        dbms_output.put_line('After trim of one indexe, Count = ' || nt.count); 
        nt.trim(2); 
        dbms_output.put_line('After trim of two indexes, Count = ' || nt.count); 
        dbms_output.put_line('NESTED TABLE ELEMENTS'); 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                   dbms_output.put_line(
                           'nt[' || i || '][' || j || '] = ' || nt(i)(j)); 
              end loop; 
        end loop; 
        nt.delete(2); 
        dbms_output.put_line(
                     'After delete of second index, Count = ' || nt.count); 
        dbms_output.put_line('NESTED TABLE ELEMENTS'); 
        loop 
              exit when v = 4; 
              for j in 1..nt.count+1 loop 
                    dbms_output.put_line(
                          'nt[' || v || '][' || j || '] = ' || nt(v)(j)); 
              end loop; 
              v := v + 1; 
              if v= 2 then 
                 v := 3; 
              end if; 
        end loop; 
        nt.delete; 
        dbms_output.put_line('After delete of 
                              entire nested table, Count = ' || nt.count); 
END; 
 
Output: 
Count = 4 
No limit to Nested Tables 
NESTED TABLE ELEMENTS 
nt[1][1] = A 
nt[1][2] = B 
nt[1][3] = C 
nt[1][4] = D 
nt[2][1] = E 
nt[2][2] = F 
nt[2][3] = G 
nt[2][4] = H 
nt[3][1] = I 
nt[3][2] = J 
nt[3][3] = K 
nt[3][4] = L 
nt[4][1] = M 
nt[4][2] = N 
nt[4][3] = O 
nt[4][4] = P 
First index = 1 
Last index = 4 
Next index = 3 
Previous index = 2 
Index 2 exists 
After extend of one index, Count = 6 
NESTED TABLE ELEMENTS 
nt[1][1] = A 
nt[1][2] = B 
nt[1][3] = C 
nt[1][4] = D 
nt[1][5] = Q 
nt[1][6] = R 
nt[2][1] = E 
nt[2][2] = F 
nt[2][3] = G 
nt[2][4] = H 
nt[2][5] = S 
nt[2][6] = T 
nt[3][1] = I 
nt[3][2] = J 
nt[3][3] = K 
nt[3][4] = L 
nt[3][5] = U 
nt[3][6] = V 
nt[4][1] = M 
nt[4][2] = N 
nt[4][3] = O 
nt[4][4] = P 
nt[4][5] = W 
nt[4][6] = X 
nt[5][1] = Y 
nt[5][2] = Z 
nt[5][3] = a 
nt[5][4] = b 
nt[5][5] = c 
nt[5][6] = d 
nt[6][1] = e 
nt[6][2] = f 
nt[6][3] = g 
nt[6][4] = h 
nt[6][5] = i 
nt[6][6] = j 
After trim of one indexe, Count = 5 
After trim of two indexes, Count = 3 
NESTED TABLE ELEMENTS 
nt[1][1] = A 
nt[1][2] = B 
nt[1][3] = C 
nt[2][1] = E 
nt[2][2] = F 
nt[2][3] = G 
nt[3][1] = I 
nt[3][2] = J 
nt[3][3] = K 
After delete of second index, Count = 2 
NESTED TABLE ELEMENTS 
nt[1][1] = A 
nt[1][2] = B 
nt[1][3] = C 
nt[3][1] = I 
nt[3][2] = J 
nt[3][3] = K 
After delete of entire nested table, Count = 0 

 
DECLARE 
       type t1 is table of varchar(2) index by binary_integer; 
       type t2 is table of t1 index by binary_integer; 
       ibt t2; 
       flag boolean; 
BEGIN 
       dbms_output.put_line('Count = ' || ibt.count); 
       if ibt.limit is null then 
           dbms_output.put_line('No limit to Index-by Tables'); 
       else 
           dbms_output.put_line('Limit = ' || ibt.limit); 
       end if; 
       ibt(1)(1) := 'a'; 
       ibt(4)(5) := 'b'; 
       ibt(5)(1) := 'c'; 
       ibt(6)(2) := 'd'; 
       ibt(8)(3) := 'e'; 
       ibt(3)(4) := 'f'; 
       dbms_output.put_line('INDEX-BY TABLE ELEMENTS'); 
       dbms_output.put_line('ibt([1][1] = ' || ibt(1)(1)); 
       dbms_output.put_line('ibt([4][5] = ' || ibt(4)(5)); 
       dbms_output.put_line('ibt([5][1] = ' || ibt(5)(1)); 
       dbms_output.put_line('ibt([6][2] = ' || ibt(6)(2)); 
       dbms_output.put_line('ibt([8][3] = ' || ibt(8)(3)); 
       dbms_output.put_line('ibt([3][4] = ' || ibt(3)(4)); 
       dbms_output.put_line('First Index = ' || ibt.first); 
       dbms_output.put_line('Last Index = ' || ibt.last); 
       dbms_output.put_line('Next Index = ' || ibt.next(3)); 
       dbms_output.put_line('Prior Index = ' || ibt.prior(8)); 
       ibt(1)(2) := 'g'; 
       ibt(1)(3) := 'h'; 
       ibt(1)(4) := 'i'; 
       ibt(1)(5) := 'k'; 
       ibt(1)(6) := 'l'; 
       ibt(1)(7) := 'm'; 
       ibt(1)(8) := 'n'; 
       dbms_output.put_line('Count = ' || ibt.count); 
       dbms_output.put_line('INDEX-BY TABLE ELEMENTS'); 
       for i in 1..8 loop 
             dbms_output.put_line('ibt[1][' || i || '] = ' || ibt(1)(i)); 
       end loop; 
       dbms_output.put_line('ibt([4][5] = ' || ibt(4)(5)); 
       dbms_output.put_line('ibt([5][1] = ' || ibt(5)(1)); 
       dbms_output.put_line('ibt([6][2] = ' || ibt(6)(2)); 
       dbms_output.put_line('ibt([8][3] = ' || ibt(8)(3)); 
       dbms_output.put_line('ibt([3][4] = ' || ibt(3)(4)); 
       flag := ibt.exists(3); 
       if flag = true then 
           dbms_output.put_line('Index 3 exists'); 
       else 
           dbms_output.put_line('Index 3 exists'); 
       end if; 
       ibt.delete(1); 
       dbms_output.put_line('After delete of first index, Count = ' || ibt.count); 
       ibt.delete(4); 
       dbms_output.put_line('After delete of fourth index, Count = ' || ibt.count); 
       dbms_output.put_line('INDEX-BY TABLE ELEMENTS'); 
       dbms_output.put_line('ibt([5][1] = ' || ibt(5)(1)); 
       dbms_output.put_line('ibt([6][2] = ' || ibt(6)(2)); 
       dbms_output.put_line('ibt([8][3] = ' || ibt(8)(3)); 
       dbms_output.put_line('ibt([3][4] = ' || ibt(3)(4)); 
       ibt.delete; 
       dbms_output.put_line('After delete 
                 of entire index-by table, Count = ' || ibt.count);    
END;  
  
Output:  
Count = 0  
No limit to Index-by Tables  
INDEX-BY TABLE ELEMENTS  
ibt([1][1] = a  
ibt([4][5] = b  
ibt([5][1] = c  
ibt([6][2] = d  
ibt([8][3] = e  
ibt([3][4] = f  
First Index = 1  
Last Index = 8  
Next Index = 4  
Prior Index = 6  
Count = 6  
INDEX-BY TABLE ELEMENTS  
ibt[1][1] = a  
ibt[1][2] = g  
ibt[1][3] = h  
ibt[1][4] = i  
ibt[1][5] = k  
ibt[1][6] = l  
ibt[1][7] = m  
ibt[1][8] = n  
ibt([4][5] = b  
ibt([5][1] = c  
ibt([6][2] = d  
ibt([8][3] = e  
ibt([3][4] = f  
Index 3 exists  
After delete of first index, Count = 5  
After delete of fourth index, Count = 4  
INDEX-BY TABLE ELEMENTS  
ibt([5][1] = c  
ibt([6][2] = d  
ibt([8][3] = e  
ibt([3][4] = f  
After delete of entire index-by table, Count = 0  

 
DECLARE 
        type t1 is table of varchar(2) index by binary_integer; 
        type t2 is table of t1 index by binary_integer; 
        type t3 is table of t2; 
        nt t3 := t3(); 
        c number := 65; 
BEGIN 
        nt.extend(2); 
        dbms_output.put_line('Count = ' || nt.count); 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                    for k in 1..nt.count loop 
                          nt(i)(j)(k) := chr(c); 
                          c := c + 1; 
                    end loop; 
              end loop; 
        end loop; 
        dbms_output.put_line('NESTED TABLE ELEMENTS'); 
        for i in 1..nt.count loop 
              for j in 1..nt.count loop 
                for k in 1..nt.count loop 
                  dbms_output.put_line(
                    'nt[' || i || '][' || j || '][' || k || '] = ' ||nt(i)(j)(k)); 
                end loop; 
              end loop; 
        end loop; 
END; 
 
Output: 
Count = 2 
NESTED TABLE ELEMENTS 
nt[1][1][1] = A 
nt[1][1][2] = B 
nt[1][2][1] = C 
nt[1][2][2] = D 
nt[2][1][1] = E 
nt[2][1][2] = F 
nt[2][2][1] = G 
nt[2][2][2] = H 

OBJECTS USED IN THE EXAMPLES

 
       SNO     SNAME          SMARKS 
  ---------- --------------  ---------- 
         1      saketh       100 
         2      srinu        200 
         3      divya        300 
         4      manogni      400 

 
 
ENAME      JOB         ADDRESS(HNO, CITY) 
---------- ---------- ----------------------------- 
Ranjit     clerk        ADDR(11, 'hyd') 
Satish     manager      ADDR(22, 'bang') 
Srinu      engineer     ADDR(33, 'kochi') 

ERROR HANDLING

• PL/SQL implements error handling with exceptions and exception handlers.
• Exceptions can be associated with oracle errors or with your own user-defined errors.
• By using exceptions and exception handlers, you can make your PL/SQL programs robust and able to deal with both unexpected and expected errors during execution.

• Compile-time errors
• Runtime errors

• Errors that occur during the compilation phase are detected by the PL/SQL engine and reported back to the user, we have to correct them.
• Runtime errors are detected by the PL/SQL runtime engine which can programmatically raise and caught by exception handlers.
• Exceptions are designed for run-time error handling, rather than compile-time error handling.

HANDLING EXCEPTIONS

• When exception is raised, control passes to the exception section of the block.
• The exception section consists of handlers for some or all of the exceptions.
• An exception handler contains the code that is executed when the error associated with the exception occurs, and the exception is raised.

	EXCEPTION
		When exception_name then
			Sequence_of_statements;
		When exception_name then
			Sequence_of_statements;
		When others then
			Sequence_of_statements;
	END;

EXCEPTION TYPES

• Predefined exceptions
• User-defined exceptions

PREDEFINED EXCEPTIONS

• Oracle has predefined several exceptions that corresponds to the most common oracle errors.
• Like the predefined types, the identifiers of these exceptions are defined in the STANDARD package.
• Because of this, they are already available to the program, it is not necessary to declare them in the declarative secion.

 
DECLARE 
        a number; 
        b varchar(2); 
        v_marks number; 
        cursor c is select * from student; 
        type t is varray(3) of varchar(2); 
        va t := t('a','b'); 
        va1 t; 
BEGIN 
          -- NO_DATA_FOUND 
          BEGIN 
              select smarks into v_marks from student where sno = 50;  
             EXCEPTION 
              when no_data_found then 
               dbms_output.put_line('Invalid student number'); 
              END; 
          -- CURSOR_ALREADY_OPEN 
          BEGIN 
            open c; 
            open c; 
            EXCEPTION 
             when cursor_already_open then 
              dbms_output.put_line('Cursor is already opened'); 
            END; 
 
           -- INVALID_CURSOR 
           BEGIN 
            close c; 
            open c; 
            close c; 
            close c; 
            EXCEPTION 
             when invalid_cursor then 
              dbms_output.put_line('Cursor is already closed'); 
            END; 
         -- TOO_MANY_ROWS 
           BEGIN 
            select smarks into v_marks from student where sno > 1;  
           EXCEPTION 
            when too_many_rows then 
             dbms_output.put_line('Too many values are coming to marks variable'); 
           END; 
         -- ZERO_DIVIDE 
         BEGIN 
          a := 5/0; 
          EXCEPTION 
           when zero_divide then 
            dbms_output.put_line('Divided by zero - invalid operation'); 
          END; 
          -- VALUE_ERROR 
          BEGIN 
           b := 'saketh'; 
          EXCEPTION 
           when value_error then 
            dbms_output.put_line('Invalid string length'); 
          END; 
          -- INVALID_NUMBER 
          BEGIN 
           insert into student values('a','srinu',100); 
          EXCEPTION 
           when invalid_number then 
            dbms_output.put_line('Invalid number'); 
          END; 
          -- SUBSCRIPT_OUTSIDE_LIMIT 
          BEGIN 
           va(4) := 'c'; 
           EXCEPTION 
            when subscript_outside_limit then 
             dbms_output.put_line('Index is greater than the limit'); 
          END; 
          -- SUBSCRIPT_BEYOND_COUNT 
          BEGIN 
           va(3) := 'c'; 
           EXCEPTION 
            when subscript_beyond_count then 
              dbms_output.put_line('Index is greater than the count'); 
           END; 
           -- COLLECTION_IS_NULL 
           BEGIN 
            va1(1) := 'a'; 
            EXCEPTION 
             when collection_is_null then 
              dbms_output.put_line('Collection is empty'); 
            END; 
           -- 
        END; 
 
Output: 
Invalid student number 
Cursor is already opened 
Cursor is already closed 
Too many values are coming to marks variable 
Divided by zero - invalid operation 
Invalid string length 
Invalid number 
Index is greater than the limit 
Index is greater than the count 
Collection is empty 

 
DECLARE 
        c number; 
BEGIN 
         c := 5/0; 
EXCEPTION 
         when zero_divide then 
                   dbms_output.put_line('Invalid Operation'); 
         when others then 
            dbms_output.put_line('From OTHERS handler: Invalid Operation'); 
END; 
 
Output: 
Invalid Operation 

USER-DEFINED EXCEPTIONS

• A user-defined exception is an error that is defined by the programmer.
• User-defined exceptions are declared in the declarative secion of a PL/SQL block.
• Just like variables, exeptions have a type EXCEPTION and scope.
• RAISING EXCEPTIONS User-defined exceptions are raised explicitly via the RAISE statement.

DECLARE
       e exception;
BEGIN
       raise e;
EXCEPTION
       when e then
                 dbms_output.put_line('e is raised');
END;
Output:
e is raised

BULIT-IN ERROR FUNCTIONS

SQLCODE AND SQLERRM

• SQLCODE returns the current error code, and SQLERRM returns the current error message text;
• For user-defined exception SQLCODE returns 1 and SQLERRM returns "user-deifned exception".
• SQLERRM wiil take only negative value except 100. If any positive value other than 100 returns non-oracle exception.

DECLARE
         e exception;
         v_dname varchar(10);
BEGIN
           -- USER-DEFINED EXCEPTION
           BEGIN
               raise e;
           EXCEPTION
               when e then
                         dbms_output.put_line(SQLCODE || ' ' || SQLERRM);
           END;

           -- PREDEFINED EXCEPTION
          BEGIN
              select dname into v_dname from dept where deptno = 50;
          EXCEPTION
              when no_data_found then
                        dbms_output.put_line(SQLCODE || ' ' || SQLERRM);
          END;
END;

Output:
1 User-Defined Exception
100 ORA-01403: no data found

BEGIN
       dbms_output.put_line(SQLERRM(100));
       dbms_output.put_line(SQLERRM(0));
       dbms_output.put_line(SQLERRM(1));
       dbms_output.put_line(SQLERRM(-100));
       dbms_output.put_line(SQLERRM(-500));
       dbms_output.put_line(SQLERRM(200));
       dbms_output.put_line(SQLERRM(-900));
END;

Output:
ORA-01403: no data found
ORA-0000: normal, successful completion
User-Defined Exception
ORA-00100: no data found
ORA-00500: Message 500 not found;  product=RDBMS; facility=ORA
-200: non-ORACLE exception
ORA-00900: invalid SQL statement

DBMS_UTILITY.FORMAT_ERROR_STACK

 
DECLARE 
     v number := 'ab'; 
BEGIN 
     null; 
EXCEPTION 
     when others then 
         dbms_output.put_line(dbms_utility.format_error_stack); 
END; 
 
 
 
Output: 
declare 
* 
ERROR at line 1: 
ORA-06502: PL/SQL: numeric or value error: character to number conversion error 
ORA-06512: at line 2 

DBMS_UTILITY.FORMAT_CALL_STACK

• This function returns a formatted string showing the execution call stack inside your PL/SQL application.
• Its usefulness is not restricted to error management;
• you will also find its handy for tracing the exectution of your code.
• You may not use this function in exception block.

 
BEGIN 
     dbms_output.put_line(dbms_utility.format_call_stack); 
END; 
 
Output: 
----- PL/SQL Call Stack ----- 

      Object_handle       line_number      object_name 
       69760478                 2           anonymous block 

DBMS_UTILITY.FORMAT_ERROR_BACKTRACE

• It displays the execution stack at the point where an exception was raised.
• Thus , you can call this function with an exception section at the top level of your stack and still find out where the error was raised deep within the call stack.

CREATE OR REPLACE PROCEDURE P1 IS
BEGIN
     dbms_output.put_line('from procedure 1');
     raise value_error;
END P1;

CREATE OR REPLACE PROCEDURE P2 IS
BEGIN
     dbms_output.put_line('from procedure 2');
     p1;
END P2;

 
CREATE OR REPLACE PROCEDURE P3 IS 
BEGIN 
     dbms_output.put_line('from procedure 3'); 
     p2; 
EXCEPTION 
     when others then 
          dbms_output.put_line(dbms_utility.format_error_backtrace); 
END P3; 

Output:
SQL> exec p3

from procedure 3
from procedure 2
from procedure 1
ORA-06512: at "SAKETH.P1", line 4
ORA-06512: at "SAKETH.P2", line 4
ORA-06512: at "SAKETH.P3", line 4

EXCEPTION_INIT PRAGMA

• Using this you can associate a named exception with a particular oracle error.
• This gives you the ability to trap this error specifically, rather than via an OTHERS handler.

DECLARE
        e exception;
        pragma exception_init(e,-1476);
        c number;
BEGIN
        c := 5/0;
EXCEPTION
        when e then
         dbms_output.put_line('Invalid Operation');
END;

Output:
Invalid Operation

RAISE_APPLICATION_ERROR

• The Boolean parameter keep_errors_flag is optional.
• If it is TRUE, the new error is added to the list of errors already raised.
• If it is FALSE, which is default, the new error will replace the current list of errors.

 
DECLARE 
        c number; 
BEGIN 
        c := 5/0; 
 
EXCEPTION 
        when zero_divide then 
             raise_application_error(-20222,'Invalid Operation'); 
END; 
 
Output: 
DECLARE 
* 
ERROR at line 1: 
ORA-20222: Invalid Operation 
ORA-06512: at line 7 

 
DECLARE 
      e exception; 
BEGIN 
       BEGIN 
          raise e; 
       END;	 
       EXCEPTION 
          when e then 
              dbms_output.put_line('e is raised'); 
END; 
 
Output: 
e is raised 

DECLARE
      e exception;
BEGIN
       BEGIN
          raise e;
        END;
END;

Output:
ERROR at line 1:
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at line 5

EXCEPTION RAISED IN THE DECLARATIVE SECTION

 
DECLARE 
      c number(3) := 'abcd'; 
BEGIN 
      dbms_output.put_line('Hello'); 
EXCEPTION 
      when others then 
          dbms_output.put_line('Invalid string length'); 
END; 
 
Output: 
ERROR at line 1: 
ORA-06502: PL/SQL: numeric or value error: character to number conversion error 
ORA-06512: at line 2 

 
BEGIN 
      DECLARE 
           c number(3) := 'abcd'; 
      BEGIN 
           dbms_output.put_line('Hello'); 
      EXCEPTION 
           when others then 
                     dbms_output.put_line('Invalid string length'); 
      END; 
EXCEPTION 
     when others then 
        dbms_output.put_line('From outer block: Invalid string length'); 
END; 
 
Output: 
From outer block: Invalid string length 

EXCEPTION RAISED IN THE EXCEPTION SECTION

DECLARE
       e1 exception;
       e2 exception;
BEGIN
       raise e1;
EXCEPTION
       when e1 then
                 dbms_output.put_line('e1 is raised');
                 raise e2;
       when e2 then
                 dbms_output.put_line('e2 is raised');
END;

Output:
e1 is raised
DECLARE
*
ERROR at line 1:
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at line 9
ORA-06510: PL/SQL: unhandled user-defined exception

 
DECLARE 
      e1 exception; 
      e2 exception; 
BEGIN 
       BEGIN 
           raise e1; 
       EXCEPTION 
           when e1 then 
                     dbms_output.put_line('e1 is raised'); 
                     raise e2; 
           when e2 then 
                     dbms_output.put_line('e2 is raised'); 
        END; 
EXCEPTION 
       when e2 then 
           dbms_output.put_line('From outer block: e2 is raised'); 
END; 
 
Output: 
e1 is raised 
From outer block: e2 is raised 

DECLARE
       e exception;
BEGIN
       raise e;
EXCEPTION
       when e then
                 dbms_output.put_line('e is raised');
                 raise e;
END;

Output:
e is raised
DECLARE
*
ERROR at line 1:
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at line 8
ORA-06510: PL/SQL: unhandled user-defined exception

RESTRICTIONS

DATABASE TRIGGERS

• Triggers are similar to procedures or functions in that they are named PL/SQL blocks with declarative, executable, and exception handling sections.
• A trigger is executed implicitly whenever the triggering event happens.
• The act of executing a trigger is known as firing the trigger.

RESTRICTIONS ON TRIGGERES

• Like packages, triggers must be stored as stand-alone objects in the database and cannot be local to a block or package.
• A trigger does not accept arguments.

USE OF TRIGGERS

• Maintaining complex integrity constraints not possible through declarative constraints enable at table creation.
• Auditing information in a table by recording the changes made and who made them.
• Automatically signaling other programs that action needs to take place when chages are made to a table.
• Perform validation on changes being made to tables.
• Automate maintenance of the database.

TYPES OF TRIGGERS

• DML Triggers
• Instead of Triggers
• DDL Triggers
• System Triggers
• Suspend Triggers

CATEGORIES

• Row level trigger fires once for each row affected by the triggering statement.
• Row level trigger is identified by the FOR EACH ROW clause.
• Statement level trigger fires once either before or after the statement.

DML TRIGGER SYNTAX

Create or replace trigger <trigger_name>
Before | after on insert or update or delete
[For each row]
Begin
	-- trigger body
End <trigger_name>;

DML TRIGGERS

• A DML trigger is fired on an INSERT, UPDATE, or DELETE operation on a database table.
• It can be fired either before or after the statement executes, and can be fired once per affected row, or once per statement.
• The combination of these factors determines the types of the triggers.
• These are a total of 12 possible types (3 statements * 2 timing * 2 levels).

ORDER OF DML TRIGGER FIRING

• Before statement level
• Before row level
• After row level
• After statement level

 
          NO   NAME     MARKS 
        ----- ------- ---------- 
         1      a         100 
         2      b         200 
         3      c         300 
         4      d         400 

CREATE OR REPLACE TRIGGER TRIGGER1
     before insert on student
BEGIN
     insert into trigger_firing_order values('Before Statement Level');
END TRIGGER1;

CREATE OR REPLACE TRIGGER TRIGGER2
     before insert on student
     for each row
BEGIN
     insert into trigger_firing_order values('Before Row Level');
END TRIGGER2;

CREATE OR REPLACE TRIGGER TRIGGER3
    after insert on student
BEGIN
    insert into trigger_firing_order values('After Statement Level');
END TRIGGER3;

CREATE OR REPLACE TRIGGER TRIGGER4
    after insert on student
    for each row
BEGIN
    insert into trigger_firing_order values('After Row Level');
END TRIGGER4;

Output:
SQL> select * from trigger_firing_order;

no rows selected

SQL> insert into student values(5,'e',500);

1 row created.

SQL> select * from trigger_firing_order;

FIRING_ORDER
--------------------------------------------------
Before Statement Level
Before Row Level
After Row Level
After Statement Level

SQL> select * from student;

        NO  NAME    MARKS
        ---- -------- ----------
         1       a         100
         2       b         200
         3       c         300
         4       d         400
         5       e         500

CORRELATION IDENTIFIERS IN ROW-LEVEL TRIGGERS

• Inside the trigger, you can access the data in the row that is currently being processed.
• This is accomplished through two correlation identifiers - :old and :new.
• A correlation identifier is a special kind of PL/SQL bind variable.
• The colon in front of each indicates that they are bind variables, in the sense of host variables used in embedded PL/SQL, and indicates that they are not regular PL/SQL variables.
• The PL/SQL compiler will treat them as records of type Triggering_table%ROWTYPE.
• Although syntactically they are treated as records, in reality they are not. :old and :new are also known as pseudorecords, for this reason.

 
 
TRIGGERING STATEMENT   	:OLD			 :NEW 
--------------------   ----------------------   -------------------------- 
INSERT		       all fields are NULL.      values that will be inserted 
                                              When the statement is completed. 
 
UPDATE		     original values for     new values that will be updated 
                     the row before the      when the statement is completed. 
                     update. 
DELETE               original values before      all fields are NULL.   
                     the row is deleted. 

CREATE OR REPLACE TRIGGER OLD_NEW
     before insert or update or delete on student
     for each row
BEGIN
     insert into marks values(:old.no,:old.marks,:new.marks);
END OLD_NEW;

 
        NO      NAME      MARKS 
       ----   -------    ------- 
         1        a         100 
         2        b         200 
         3        c         300 
         4        d         400 
         5        e         500 

 
        NO      NAME     MARKS 
       ----    ------   ------- 
         1       a         100 
         2       b         200 
         3       c         300 
         4       d         400 
         5       e         500 
         6       f         600 

 
        NO  OLD_MARKS  NEW_MARKS 
        ---- --------  --------- 
                         600 

 
        NO    NAME       MARKS 
      -----  -------    ------- 
         1       a         100 
         2       b         200 
         3       c         300 
         4       d         400 
         5       e         555 
         6       f         600 

 
  NO   OLD_MARKS   NEW_MARKS 
 ---- ----------  ----------- 
                     600 
  5     500          555 

 
        NO     NAME   MARKS 
       ----   ------ ---------- 
         1        a     100 
         3        c     300 
         4        d     400 
         5        e     555 
         6        f     600 

 
        NO   OLD_MARKS   NEW_MARKS 
       ----  ---------- ---------------- 
                                 600 
         5      500              555 
         2      200 

REFERENCING CLAUSE

 
CREATE OR REPLACE TRIGGER REFERENCE_TRIGGER 
      before insert or update or delete on student 
      referencing old as old_student new as new_student 
      for each row 
BEGIN 
      insert into marks      
         values(:old_student.no,:old_student.marks,:new_student.marks); 
END REFERENCE_TRIGGER; 

WHEN CLAUSE

 
CREATE OR REPLACE TRIGGER WHEN_TRIGGER 
      before insert or update or delete on student 
      referencing old as old_student new as new_student 
      for each row 
      when (new_student.marks > 500) 
BEGIN 
      insert into marks      
         values(:old_student.no,:old_student.marks,:new_student.marks); 
END WHEN_TRIGGER; 

TRIGGER PREDICATES

• INSERTING
• UPDATING
• DELETING

CREATE OR REPLACE TRIGGER PREDICATE_TRIGGER
       before insert or update or delete on student
BEGIN
       if inserting then 
          insert into predicates values('I');
       elsif updating then 
               insert into predicates values('U');
       elsif deleting then
               insert into predicates values('D');
       end if;
END PREDICATE_TRIGGER;

Output:
SQL> delete student where no=1;

1 row deleted.


SQL> select * from predicates;


MSG
---------------
D

SQL> insert into student values(7,'g',700);

1 row created.

SQL> select * from predicates;

MSG
---------------
D
I

SQL> update student set marks = 777 where no=7;

1 row updated.

SQL> select * from predicates;


MSG
---------------
D
I
U

INSTEAD-OF TRIGGERS

• To allow a view that would otherwise not be modifiable to be modified.
• To modify the columns of a nested table column in a view.