BEFORE INSERT TRIGGER and DELETE FROM

Please assist me with this. I'm trying to restrict an INSERT INTO to the products table based on if the new item's product_price makes the sum(product_price) exceed a certain amount. The trigger gets created properly but the INSERT will still insert the new record. What did I do wrong?

CREATE OR REPLACE TRIGGER insert_product BEFORE INSERT ON products FOR EACH ROW
DECLARE
new_id NUMBER;
total_price NUMBER;
cannot_change EXCEPTION;
BEGIN
SELECT sum(product_price) + :NEW.product_price INTO total_price FROM products;
IF (total_price > 160) THEN
RAISE cannot_change;
END IF;
EXCEPTION WHEN cannot_change THEN
DELETE FROM products WHERE product_id = :NEW.product_id; dbms_output.put_line('Cannot Insert Item'); END insert_product;
/ Received on Wed Nov 06 2002 - 02:56:54 CET