Oracle PL/SQL-Tipps

DROP TABLE scott.emp_trig;
CREATE TABLE scott.emp_trig
   AS
       SELECT
           *
       FROM
           scott.emp;
col cmode format A6 col user_name format a10 col sal format 9999
DROP TABLE scott.emp_audit;
CREATE TABLE scott.emp_audit
   AS
       SELECT
           *
       FROM
           scott.emp
       WHERE
           1 = 2;
ALTER TABLE scott.emp_audit ADD (
   old_sal     NUMBER(7, 2),
   new_sal     NUMBER(7, 2),
   user_name   VARCHAR2(30),
   change_date DATE,
   event       CHAR(1)
);
CREATE OR REPLACE TRIGGER scott.emp_trig_idu BEFORE
   INSERT OR UPDATE OR DELETE ON scott.emp_trig
   FOR EACH ROW
DECLARE
   v_event CHAR(1) := 'X';
BEGIN
   IF inserting THEN
       v_event := 'I';
   ELSIF updating THEN
       v_event := 'U';
   ELSE --DELETING 
       v_event := 'D';
   END IF;
   INSERT INTO scott.emp_audit (
       empno,
       old_sal,
       new_sal,
       user_name,
       change_date,
       event
   ) VALUES (
       :old.empno,
       :old.sal,
       :new.sal,
       user,
       sysdate,
       v_event
   );
END;
/