mysql - 在同一张表上更新后在触发器中更新表

Question

如何在同一个表上更新后在触发器中更新表的列？
这里是触发器:

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)

现在当我像这样更新表格时

UPDATE products_score SET votes_1 = 5 WHERE id = 0

这不起作用，因为我得到以下信息:

#1442 - Can't update table 'products_score' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.

那么我到底该如何让它发挥作用呢？

Answer 1

如果您将触发器更改为 BEFORE 而不是 AFTER 您可以这样做:

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
;