Hi all,
I have sample code to find duplicate values when enter, but i don't know in which trigger to use? can you please explain and why we use in that trigger?
DECLARE
cnt NUMBER (5);
BEGIN
SELECT Count (*)
INTO cnt
FROM emp
WHERE empno = :emp.empno;
IF cnt > 0 THEN
Message ('the empno is already existing ');
ELSE
next_item;
END IF;
END;