Hi,
I'd like to change message:
ORA-00001: unique constraint (SCOTT.PK_DEPT) violated

if I create a procedure:
begin
INSERT INTO DEPT ( DEPTNO, DNAME, LOC ) VALUES (
10, 'aaaa', 'bbbbb');
exception
when dup_val_on_index then
raise_application_error( -20100, 'change your value please!' );
end;

it run correctly.

But I'd like to create a trigger that fire when I insert a new record.

I tried this:
CREATE OR REPLACE TRIGGER dept_test
after INSERT ON dept
FOR EACH ROW
BEGIN
if inserting then
null;
end if;
exception
when dup_val_on_index then
raise_application_error( -20100, 'cambia il tuo valore, esiste' );
END dept_TEST;

but It doesn't run

How can I create this trigger??

Thanks
Raf