Oracle Forms creates this trigger automatically when you define a master/detail relation and set the Delete Record Behavior property to Non-Isolated. It fires when there is an attempt to delete a record in the master block of a master/detail relation.
Definition Level form or block
Any command, unrestricted Built-ins, restricted Built-ins
Enter Query Mode no
Prevents the deletion of the current master record
Master/Detail Coordination
The following example replaces the On-Check-Delete-Master that is generated by default for a master/detail relation with a trigger that will fail if the sum of the distributions does not equal the purchase order total.
DECLARE
the_sum NUMBER;
BEGIN
SELECT SUM(dollar_amt)
INTO the_sum
FROM po_distribution
WHERE po_number = :purchase_order.number;
/* Check for errors */
IF the_sum <> :purchase_order.total THEN
Message('PO Distributions do not reconcile.');
RAISE Form_Trigger_Failure;
ELSIF form_fatal OR form_failure THEN
raise form_trigger_failure;
end if;
END;