توضیحات
BEFOR DELETE Trigger به معنی این است که قبل از اجرای یک دستور delete، یک تریگر فعال (fire) شود.دستور
دستور Befor delete triger به صورت زیر نوشته میشود:|
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CREATE [ OR REPLACE ] TRIGGER trigger_nameBEFORE DELETE ON table_name [ FOR EACH ROW ]DECLARE -- variable declarationsBEGIN -- trigger codeEXCEPTION WHEN ... -- exception handlingEND; |
مثال
مثالی از دستور ساخت Befor Delete triger را مشاهده میکنیم:|
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CREATE TABLE orders( order_id number(5), quantity number(4), cost_per_item number(6,2), total_cost number(8,2));CREATE OR REPLACE TRIGGER orders_before_deleteBEFORE DELETE ON orders FOR EACH ROWDECLARE v_username varchar2(10);BEGIN -- Find username of person performing the DELETE on the table SELECT user INTO v_username FROM dual; -- Insert record into audit table INSERT INTO orders_audit ( order_id, quantity, cost_per_item, total_cost, delete_date, deleted_by ) VALUES ( :old.order_id, :old.quantity, :old.cost_per_item, :old.total_cost, sysdate, v_username );END; |