CREATE OR REPLACE TRIGGER TR_BM_CKBM00_NHXYY
 BEFORE
 UPDATE
 ON BM_CKBM00
 REFERENCING OLD AS OLD NEW AS NEW
 FOR EACH ROW
BEGIN
   IF :new.ZT0000 <> :old.ZT0000
      THEN
        raise_application_error(-20020,'ZT0000不允许修改，请联系管理员');

   END IF;
END;