Need Help in a Oracle Issue

Question

Hi need some valuable suggestion.
I have a table myemp with columns empno, ename, hiredate. I altered the table and added a new column as create_dt.
The requirement is that wherenver i update or insert a new row into myemp table, the column create_dt should get filled with the values of hiredate of myemp table(same table).
This is a case of multi row updates. Triggers are feasible?
Please guide me.
Thanks in advance.

Answer 1

SID,
I think what you need is "INSTEAD OF TRIGGERS" implementation . Now question whethere triggers are feasible or not depends upon how often changes being made meaning entering new hire information ( I guess not hiring several thousand or laying off 100 of people everyday). :)
Here what you can do and customized trigger according to your needs
Prompt Table MYEMP;
CREATE TABLE MYEMP
  EMPNO       NUMBER(10)                            NULL,
  ENAME       VARCHAR2(50 BYTE)                     NULL,
  HIREDATE    DATE                                  NULL,
  SAL         NUMBER(10,2)                          NULL,
  CREATE_DTE  DATE                                  NULL
Create view and instead of trigger_
CREATE OR REPLACE FORCE VIEW vmyemp (
   empno,
   ename,
   hiredate,
   sal,
   create_dte
AS
   SELECT "EMPNO", "ENAME", "HIREDATE", "SAL", "CREATE_DTE"
   FROM myemp;
Prompt drop Trigger V_EMP;
DROP TRIGGER V_EMP;
Prompt Trigger V_EMP;
CREATE OR REPLACE TRIGGER v_emp
   INSTEAD OF INSERT OR UPDATE
   ON VMYEMP    FOR EACH ROW
DECLARE
   tmpvar   NUMBER;
BEGIN
   IF INSERTING
   THEN
      INSERT INTO myemp
         empno, ename, hiredate, sal, create_dte
      VALUES (:new.empno, :new.ename, :new.hiredate, :new.sal, :new.hiredate);
   ELSIF UPDATING
   THEN
      UPDATE myemp
      SET create_dte = :NEW.hiredate
      WHERE empno = :old.empno;
   END IF;
EXCEPTION
   WHEN OTHERS
   THEN
      -- Consider logging the error and then re-raise
      RAISE;
END v_emp;Regards
Edited by: OrionNet on Jan 16, 2009 1:11 PM