PLSQL FORWARD DECLERATION

FORWARD DECLERATION

Before going to use the procedure in any other subprogram or other block , you must declare the prototype of the procedure in declarative section.

Ex1:                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

Ex2:

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