table mutating problem (trigger)

:confused: I have my trigger that run correctly without errors - but when I want to test it with : delete emp where deptno = 20;
it is giving me an error :
table xxx.EMP is mutating, trigger/function may not see it

the trigger does : when given a deptno it delete the dept of this emp (records of emp with deptno)

Help please.... Thanks!

here is the code:

show errors;

create or replace trigger deleteDEPT
after delete on EMP
for each row
declare
v_deptno EMP.deptno%Type;
counter EMP.deptno%Type;
begin
select count(*) into counter from EMP
where EMP.deptno = :OLD.deptno;
if counter = 0 then
delete DEPT;
--delete_dept(v_deptno);
end if;
end;
/


I tried to use this to resolve the problem, but nothing.


ALTER TABLE emp DROP CONSTRAINT fk_dept_deptno;
ALTER TABLE emp ADD (
CONSTRAINT fk_dept_deptno
FOREIGN KEY (DEPTNO)
REFERENCES DEPT(DEPTNO) ON DELETE CASCADE
);

This is happening because trigger is attempting to access OLD.deptno after delete.

Quote:

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Originally Posted by PAVB

This is happening because trigger is attempting to access OLD.deptno after delete.

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No its happening because he is causing a mutating table error by selecting on the same table that this trigger is written on. :confused:

Code:

---

select count(*) into counter from EMP
where EMP.deptno = :OLD.deptno;

---

Thom,

You need the row level trigger to insert rows into a temporary table based on a transaction id. Then write an after delete statement trigger to query the rows deleted and delete any departments that no longer have any employees. You might also considered just marking the departments as defunct because you may have other records that are dependent on the department even though no one works in that department.