Emulate casscade update and delete

casscade_emul_trigger.sql

CREATE OR REPLACE FUNCTION casscade_func() RETURNS TRIGGER AS $$
DECLARE
	exist boolean;
BEGIN
    IF TG_OP = 'UPDATE' THEN
	IF OLD.id <> NEW.id THEN
		UPDATE tc_order SET customer_id=NEW.id WHERE customer_id=OLD.id;
	END IF;
        RETURN NEW;
    ELSIF TG_OP = 'DELETE' THEN
	exist :=  exists(SELECT customer_id FROM tc_order WHERE customer_id=OLD.id);
	IF exist THEN
		DELETE FROM tc_order WHERE customer_id=OLD.id;
	END IF;
        RETURN OLD;
    END IF;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER trigger_tc_customer
AFTER UPDATE OR DELETE ON tc_customer FOR EACH ROW EXECUTE PROCEDURE casscade_func();