Oracle 10g列掩码与关系视图比较

CREATE OR REPLACE 

FUNCTION rls_dept (obj_owner IN VARCHAR2, obj_name IN VARCHAR2)

RETURN VARCHAR2 

AS
   deptno                       NUMBER;
   predicate                    VARCHAR2(200);

BEGIN
   deptno := SYS_CONTEXT('HR_CONTEXT','DEPT');
   IF deptno IS NULL THEN
      predicate := '1=2';
   ELSE
      predicate := 'department_id = '||deptno;
   END IF;


   RETURN (predicate);

END rls_dept;

/