Question

我有一张简单的牌桌：

CREATE TABLE `users_individual_cards` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` char(36) NOT NULL,
  `individual_card_id` int(11) NOT NULL,
  `own` int(10) unsigned NOT NULL,
  `want` int(10) unsigned NOT NULL,
  `trade` int(10) unsigned NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `user_id` (`user_id`,`individual_card_id`),
  KEY `user_id_2` (`user_id`),
  KEY `individual_card_id` (`individual_card_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1;

我有ajax来添加和删除基于OWN，WANT和TRADE的记录。但是，如果用户删除了所有OWN，WANT和TRADE卡，它们将归零，但会将记录留在数据库中。我希望删除记录。在每次“更新”后检查是否所有列= 0是唯一的方法吗？或者我可以使用以下内容设置条件触发器：

//psuedo sql
AFTER update IF (OWN = 0, WANT = 0, TRADE = 0) DELETE

最好的方法是什么？你能帮忙解决这个问题吗？

Answer 1

为什么不从PHP（或其他前端）发出两个查询？

update `users_individual_cards` ...
delete `users_individual_cards` where ... (same condition) and own + want + trade = 0

Answer 2

触发器将是：

CREATE TRIGGER users_individual_cards_trigger
    AFTER UPDATE ON users_individual_cards
    FOR EACH ROW
    BEGIN
    DELETE FROM users_individual_cards
    WHERE 'OWN' = 0 AND 'WANT' = 0 AND 'TRADE' = 0;
    END$$

解决方案抛出删除查询会更好，因为并非所有版本的mysql都支持它。

当某些列= 0时动态删除记录;数据清理

2 个答案: