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Functions

Usage : It is used for performing the calculations.. and evaluating an expr..

Note :

* Functions can be executed from->A select statement->SQL Prompt->Anonymous and Named Blocks..

Whenever the user defined functions are used in a select statement thesefunctions will act as a single row expr.. and as a result they will return asingle value per row retrieved by that statement..

Restrictions on Functions which are targeted to be used in a select statement.:

-> Datatypes used in a function should be only oracle server specific datatypes..

-> DML Operations and TCL are restricted in a function if it is targetted to aSelect statement.

-> Return value is must in a function... even in the exception handlingStatements..

-> Output statements return in a function will not work if it used in a selectStatement..

--> Syntax :

create [or replace] function function_name[( arg [in | out | in out] [nocopy] )( arg [in | out | in out] [nocopy] ) ]

return is / as

--local variable declarations--executable statement(s)return ;[exception]--exception handling statement(s) [function_name];

--> Create or replace function addnum( a number, b number )return number

isbegin

return a+b;end;

--> Executing function from select statement :

-> Select addnum(10,20) from dual;

-> Select empno,ename,sal,deptno,comm,addnum( sal, nvl(comm,0)) as "Total Salary"from emp

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Note : The information about the stored procedures can be retrievedfrom user_objects..

--> Select object_name , object_type ,statusfrom user_objectswhere object_name like 'ADDNUM'

The source of the stored procedures can be retrieved from user_source

--> Select text from user_source[all_source][, dba_source]where name like 'ADDNUM';

--> Create or replace function getannsal( eno number ) return numberistsal number;beginSelect sal into tsal from empwhere empno = eno;return tsal*12;end;

--> Select empno,ename,sal,deptno,getannsal(empno) as "Annual Salary"from emp

--> Executing the functions from the SQL Prompt :

-> Declare a bind variable

variable annsal number

-> Execute the function :

Syntax : exec :bind_variable := function_name( [arg_value(s)] )

exec :annsal := getannsal( 7788 );

-> Print the value of the bind variable :

Syntax: print variable_name

ex : print annsal

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Exceptions :

These are the runtime errors which are raised based on the invalid value(s) provided by the user.. at the runtime..

create or replace function divnum( a number, b number ) return numberis

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beginreturn a/b;exceptionwhen zero_divide thendbms_output.put_line( 'Oops!.. cant divide number by Zero... ' );end;

declarea number := &a;b number := &b;res number;beginres := divnum(a , b );dbms_output.put_line( 'Result : ' || res );end;

create or replace function getsalary( name emp.ename%type )return emp.sal%typeistsal emp.sal%type;beginselect sal into tsal from empwhere ename like name;

return tsal;exceptionwhen no_data_found thendbms_output.put_line( 'Oops!.. Employee doesnot exists..' );return -1;when too_many_rows thendbms_output.put_line( 'I OOOO... i got confused too many records found...' );return -2;end;

variable salary number;

exec :salary := getsalary( 'SMITH' );

print salary

exec :Salary := getsalary( 'USHA' );

select empno,ename,getsalary( ename ) as "Sal"from emp

select getsalary('RAMIYA') from dual;