Need Guidance with writing MySQL Trigger - mysql

Question

I'll admit, up front, that this is my first MySQL trigger. The MySQL version is 8.0.
I have a table for orders and order line items. In the orders table I have a column that stores the total of all line items. I need a trigger that updates that total every time a line items is added or changed for that order. Here's what I have so far:
CREATE TRIGGER update_line_item_total
AFTER INSERT
ON orderlines.price FOR EACH ROW
BEGIN
-- variable declarations
DECLARE li_order_id INT;
DECLARE li_total DEC;
SET li_order_id = orderlines.order_id;
SET li_total = SUM (orderlines.price) WHERE orderlines.order_id = li_order_id;
-- trigger code
UPDATE orders SET
total_lineitems = li_total
WHERE orders.order_id = li_order_id;
END;
I put this into MySQL Workbench and it was rejected. I know that the DECLARE statements, the 2nd SET statement, and the END statements were the ones flagged as incorrect, however I'm not even sure where to look to find out what's wrong.
Looking for guidance and direction.
Thanks,
Michael Frankel
Wizard Consulting Group, Inc.

Answer 1

your problem is on this line : SET li_total = SUM (orderlines.price) WHERE orderlines.order_id = li_order_id;
add delimiters.
do this :
delimiter |
CREATE TRIGGER update_line_item_total
AFTER INSERT
ON orderlines.price FOR EACH ROW
BEGIN
-- variable declarations
DECLARE li_order_id INT;
DECLARE li_total DEC;
declare li_total_temp dec;
SET li_order_id = orderlines.order_id;
select orderlines.price into li_total_temp WHERE orderlines.order_id = li_order_id;
SET li_total = li_total + li_total_temp;
-- trigger code
UPDATE orders SET
total_lineitems = li_total
WHERE orders.order_id = li_order_id;
END |
delimiter ;