存储过程 IF包含字段判断

CREATE OR REPLACE FUNCTION F_C_GETRES
(RES IN VARCHAR2,
 M_MO_NUMBER IN VARCHAR2,
 M_EMP IN VARCHAR2)
RETURN VARCHAR
IS
L_RES VARCHAR (4000);
BEGIN
IF INSTR(RES,'OK')>0 THEN
  L_RES:=RES||'##1&';
  IF M_MO_NUMBER IS NOT NULL THEN
    IF M_EMP IS NULL THEN
      L_RES:=L_RES||'&'||M_MO_NUMBER;
    ELSE
      L_RES:=L_RES||'&'||M_MO_NUMBER||','||M_EMP;
      END IF;
    END IF;
ELSIF INSTR(RES,'NG')>0 THEN
  L_RES:=RES||'##0&';
ELSE
  L_RES:=RES;
END IF;

RETURN
L_RES;
END F_C_GETRES;