Question

更新该表后，我试图填充表中的空白字段，但出现此错误：

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

我该如何解决？

我的触发器的查询：

DELIMITER $$
Create trigger OfferSum 
after UPDATE
on Services_Offer
FOR EACH ROW
BEGIN
    UPDATE Services_Offer
    SET NEW.final_price = 
    (SELECT service_price from Services_Level
    where Services_Level.level_code= Services_Offer.level_code)*Services_Offer.service_size;

END$$

Answer 1

我认为您需要在之前更新触发器：

DELIMITER $$

CREATE TRIGGER OfferSum BEFORE UPDATE ON Services_Offer
FOR EACH ROW
BEGIN
    SELECT NEW.final_price := sl.service_price * NEW.service_size
    FROM Services_Level sl
    WHERE sl.level_code = NEW.level_code;
END$$

Answer 2

为什么您需要为此触发？看起来上面的查询将导致无限循环。每次更新一行时，它都会调用一个更新触发器，该触发器实际上会更新表，从而一次又一次地触发该触发器，直到崩溃。

相反，为什么不与初始更新一起计算和更新列。查询如下所示：

UPDATE Services_Offer 
SET 
    column1 = value1, 
    column2 = value2, 
    final_price = 
      ( 
        SELECT service_price 
        FROM Services_Level 
        WHERE Services_Level.level_code = Services_Offer.level_code
      ) * service_size
WHERE id = XXX

其中column1 = value1，column2 = value2来自您的初始更新查询。

我无法在mysql中使用触发器更新表

2 个答案: