我有几个表:
-
users
充满了用户。 -
item
到处都是物品。 -
item
可以有多个second_item
。 -
users
能够通过表users_items
进行second_item
。
当我删除item
所有second_item
和users_items
也应该被删除。因此,我设置了一些应该删除子表记录的约束。但它在users_items
留下了记录.
这是我的MySQL查询:
CREATE TABLE `item` (
`id` int(10) UNSIGNED NOT NULL,
`name` varchar(63) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `item` (`id`, `name`) VALUES (1, 'test');
CREATE TABLE `second_item` (
`id` int(10) UNSIGNED NOT NULL,
`item_id` int(10) UNSIGNED DEFAULT NULL,
`name` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `second_item` (`id`, `item_id`, `name`) VALUES
(1, 1, 'test');
CREATE TABLE `users` (
`id` int(10) UNSIGNED NOT NULL,
`email` varchar(200) DEFAULT NULL,
`password` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `users` (`id`, `email`, `password`) VALUES (1, 'test', 'test');
CREATE TABLE `users_items` (
`id` int(10) UNSIGNED NOT NULL,
`user_id` int(10) UNSIGNED DEFAULT NULL,
`item_id` int(10) UNSIGNED DEFAULT NULL,
`item_second_id` int(10) UNSIGNED DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `users_items` (`id`, `user_id`, `item_id`, `item_second_id`) VALUES (1, 1, 1, 1);
ALTER TABLE `second_item`
ADD PRIMARY KEY (`id`),
ADD KEY `item_id` (`item_id`);
ALTER TABLE `item` ADD PRIMARY KEY (`id`);
ALTER TABLE `users` ADD PRIMARY KEY (`id`);
ALTER TABLE `users_items`
ADD PRIMARY KEY (`id`),
ADD KEY `user_id` (`user_id`),
ADD KEY `item_id` (`item_id`),
ADD KEY `item_second_id` (`item_second_id`);
ALTER TABLE `second_item`
ADD CONSTRAINT `constraint1` FOREIGN KEY (`item_id`) REFERENCES `item` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
ALTER TABLE `users_items`
ADD CONSTRAINT `constraint2` FOREIGN KEY (`item_id`) REFERENCES `item` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
ADD CONSTRAINT `constraint3` FOREIGN KEY (`item_second_id`) REFERENCES `second_item` (`id`) ON DELETE SET NULL ON UPDATE CASCADE,
ADD CONSTRAINT `constraint4` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
我尝试执行以下删除查询,但它在users_items
中留下了一条记录:
DELETE FROM `item` WHERE `item`.`id` = 1;
这个"错误"发生在:
- WAMP (服务器版本: 5.7.16 - MySQL Community Server (GPL((
- UBUNTU (5.7.20-0ubuntu0.16.04.1 - (Ubuntu((
编辑:
该错误是由您添加约束的顺序引起的:
ALTER TABLE `users_items`
ADD CONSTRAINT `constraint1` FOREIGN KEY (`item_id`) REFERENCES `item` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
ADD CONSTRAINT `constraint2` FOREIGN KEY (`item_second_id`) REFERENCES `second_item` (`id`) ON DELETE SET NULL ON UPDATE CASCADE,
ADD CONSTRAINT `constraint3` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
ALTER TABLE `second_item`
ADD CONSTRAINT `constraint4` FOREIGN KEY (`item_id`) REFERENCES `item` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
这样它就是固定的。
我确实得到了和你一样的结果。还找到了修复;)
更改 SQL 代码中约束的顺序。这将解决您的问题。
我认为这是一个奇怪的MySQL错误