SQL & PL/SQL

HI,

How to append following child parts to main sql (select statement)?

   PROCEDURE DisplayEmpPect (
      input_Type     IN       VARCHAR2,
      resultset      OUT      cur_ga
   )
   IS
   BEGIN
      OPEN resultset FOR

	If input_Type = "A" Then
         SELECT SUM (E.Salary) AS Sal
           FROM HEMP E
	ELSE If input_Type = "B" Then
	    WHERE E.EMP = 'ALL'
	ELSE
	    WHERE E.EMP = 'ALL'
		AND E.Type = 'Cont'
	END IF
   END;

Note: The query that I gave in procedure is not actual query, actual query is very big and has many conditions in it. I just need an idea
to append query parts to main select based on conditions.

Thanks