Updating table in trigger after update on the same table
How can I update table's column in a trigger after update on the same table? Here's the trigger:
CREATE TRIGGER upd_total_votes AFTER UPDATE ON products_score FOR EACH ROW UPDATE products_score SET products_score.votes_total = (SELECT (votes_1 + votes_2 + votes_3 + votes_4 + votes_5) FROM products_score WHERE id = new.id)
Now when I update the table like
UPDATE products_score SET votes_1 = 5 WHERE id = 0
this doesn't work, as I get the following:
#1442 - Can't update table 'products_score' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
So how on earth I can get this to work?
If you change your trigger to BEFORE instead of AFTER you could do it like this:
CREATE TRIGGER upd_total_votes BEFORE UPDATE ON products_score FOR EACH ROW BEGIN SET new.votes_total = new.votes_1 + new.votes_2 + new.votes_3 + new.votes_4 + new.votes_5 END ;
You can't have this the way you have setup because a trigger can't query other rows of the same table that it is defined on. Istead you can use a Before Update Trigger toachieve what you want:
CREATE TRIGGER upd_total_votes BEFORE UPDATE ON products_score FOR EACH ROW BEGIN SET NEW.votes_total = NEW.votes_1 + NEW.votes_2 + NEW.votes_3 + NEW.votes_4 + NEW.votes_5; END;
Or use a stored procedure to update the table.