MySQL update after insert trigger - mysql

Question

I am new to triggers but have coded this one
DELIMITER $$
CREATE TRIGGER stockupdate
AFTER INSERT ON inventory.orderdetails
FOR EACH ROW
BEGIN
UPDATE inventory.stockitem s
INNER JOIN inventory.OrderDetails d ON s.ID = d.Item
INNER JOIN inventory.orders o ON ebayOrderNumber = d.OrderNumber
SET s.`Sold Date` = o.`Order Date`, s.EbayOrderNumber = o.ebayOrderNumber, s.`Sale Price` = d.Price
WHERE s.ID = d.Item;
END$$
DELIMITER ;
Currently it does not update table stockitem as expected. Is there anything glaringly obvious that I have done wrong please?
Many thanks for looking.

Answer 1

That's because your join returns all or most records from oderDetails and oders table and you are not supressing sql_safe_updates safety feature.
You are definitely missing table alias in o ON ??.ebayOrderNumber = d.OrderNumber. Besides, WHERE s.ID = d.Item; is redundant as your table joins already do that. Your Where condition should be more explicit and tell which stock item to update.
DELIMITER $$
CREATE TRIGGER stockupdate AFTER INSERT ON inventory.orderdetails FOR EACH ROW
BEGIN
UPDATE
(inventory.stockitem s
INNER JOIN inventory.OrderDetails d ON s.ID = d.Item)
INNER JOIN inventory.orders o ON o.ebayOrderNumber = d.OrderNumber
SET
s.`Sold Date` = o.`Order Date`, -- update the stock
s.EbayOrderNumber = o.ebayOrderNumber,
s.`Sale Price` = d.Price
WHERE
d.orederNumber = NEW.OrderNumber, -- From this order
d.Item = NEW.item; -- and this item id
END$$
DELIMITER ;
Having said that, I do not understand why would you want to update the stock table with a sold price? orderDetails already contains those for you and what if you have many quantity for a single stock? i.e 100 Dell laptops. Surely you don't have 100 records for each Dell laptop in your stock item? and updating each record with sold price? Anyway i leave that up to you..