Processing Triggers - part 2

Question

Hello,
I would like to solve the following problem using triggers:
I need to change the DeptNo for all Emps working for Dept 20 to 50;
Trigger (or triggers) has to create Deptno 50 and copy the data from DeptName (dname) and DeptLocation (loc) to new row Where DeptNo is 50;
After that, the old DeptNo 20 has to be deleted from Dept.
The following triggers works fine:
-- step 1 --
Create or Replace Trigger TrigEmp
Before Insert or Update On Emp
For each row
Begin
INSERT INTO dept(deptno)
SELECT :NEW.deptno
FROM dual
WHERE NOT EXISTS (SELECT NULL
FROM dept
WHERE deptno = :NEW.deptno);
End;
-- step 2 --
Create or Replace Trigger TrigDept
Before Insert or Update of Deptno On Dept
For each row When(new.Deptno=50)
Begin
:New.dname := 'Sunshine';
:New.loc := 'Hawaii';
End;
The problem I have with step 3 because I have to perform DML (Delete) operation on Dept withing a trigger and I get "Mutating" error again...))
Is there any way to solve it?
Thank you for your consideration
P.S. I am still using 9i

Answer 1

I found the solution anyway!
Here is the code:
Create or Replace Trigger TrigEmp
Before Insert or Update On Emp
For each row
Begin
INSERT INTO dept(deptno)
SELECT :NEW.deptno
FROM dual
WHERE NOT EXISTS (SELECT NULL
FROM dept
WHERE deptno = :NEW.deptno);
End;
Create or Replace Trigger TrigDept
Before Insert or Update of Deptno On Dept
For each row When(new.Deptno=50)
Begin
:New.dname := 'Sunshine';
:New.loc := 'Hawaii';
End;
Create or replace Procedure delete_dept
(Message in varchar2) is
BEGIN
DBMS_OUTPUT.PUT_LINE(Message);
END;
Create or replace trigger TrigDept2
After insert or update of DeptNo on Dept
For each row When(new.Deptno=50)
Begin
delete_dept(' ! Message for DBA - All data copied into new Dept - Deptno 20 deleted !');
End;
Create or replace trigger TrigDept3
After insert or update on Emp
For each row When(old.Deptno=20)
Begin
delete from dept
where deptno=20;
End;
runs fine and tables are not mutating anymore...!!
the idea was only to learn how to create triggers, nothing more...
I know how to create triggers using form builder in developer suite but it is always nice to understand what processes run under when you press buttons...))
thank you for help...