What is the difference betwee decode & case function

Question

Hi
What is the difference betwee decode & case function
1.decode can't used in pl/sql 1) case can be user
2.in decode we can't use (>,<,>=) 2) we can use
any other do u have....
thanks in advance....

Answer 1

DECODE works with expressions which are scalar values.
CASE can work with predicates and subqueries in searchable form.
There is one more Important difference between CASE and DECODE
DECODE can be used Only inside SQL statement....
But CASE can be used any where even as a parameter of a function/procedure
Eg:-
SQL> create or replace procedure pro_01(n number) is
  2  begin
  3  dbms_output.put_line(' The number  = '||n);
  4  End;
  5  /
Procedure created.
SQL> set serverout on
SQL> var a varchar2(5);
SQL> Begin
  2  :a := 'ONE';
  3  End;
  4  /
PL/SQL procedure successfully completed.
SQL> Begin
  2   pro_01(Decode(:a,'ONE',1,0));
  3  End;
  4  /
pro_01(Decode(:a,'ONE',1,0));
ERROR at line 2:
ORA-06550: line 2, column 9:
PLS-00204: function or pseudo-column 'DECODE' may be used inside a SQL
statement only
ORA-06550: line 2, column 2:
PL/SQL: Statement ignored
SQL> Begin
  2    pro_01(case :a when 'ONE' then 1 else 0 end);
  3  End;
  4  /
The number  = 1
PL/SQL procedure successfully completed.Message was edited by:
Avi
Message was edited by:
Avi