Oracle user-defined functions

Oracle Function Format:
Create or replace function user-defined function name [(parameter)]
Return Value Type
Is
Return Value Type
Begin
Operation
End;

Test:
Input empno to obtain the user name,
CREATE OR REPLACE
FUNCTION FUN_SEL (aa emp. EMPNO % TYPE) RETURN VARCHAR2
E_NAME EMP. ENAME % TYPE;
BEGIN
Select ename into E_NAME from emp where empno = AA;
RETURN E_NAME;
END FUN_SEL;

Call the function code in sqlplus:

SQL> var put varchar2 (100)
SQL> exec: put: = fun_sel (7861 );
PL/SQL procedure successfully completed
Put
---------
Tom
SQL> print put;
Put
---------
Tom

Preface"