在同一个表上更新后更新触发器中的表

How can I update table's column in a trigger after update on the same table?
Here's the trigger:

在更新同一个表之后，如何在触发器中更新表的列?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)

Now when I update the table like

现在当我更新表时


UPDATE products_score SET votes_1 = 5 WHERE id = 0

this doesn't work, as I get the following:

这是行不通的，因为我有以下几点:

#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?

那么，我到底怎么才能让它发挥作用呢?

2 个解决方案

#1

If you change your trigger to BEFORE instead of AFTER you could do it like this:

如果你把你的触发器改成BEFORE而不是AFTER你可以这样做:

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
;

#2

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:

你不能用你设置的方式来设置，因为触发器不能查询它所定义的同一表的其他行。你可以使用一个前更新触发器来实现你想要的:

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.

或者使用存储过程更新表。

#1