MySQL - 无法添加或更新子行：外键约束失败 [英] MySQL - Cannot add or update a child row: a foreign key constraint fails

问题描述

这似乎是一个常见的错误，但对我来说，我无法弄清楚这一点。

我在MySQL中有一组InnoDB用户表通过外键捆绑在一起;父$ 用户表和一组存储电子邮件地址，动作等的子表。这些都与父 user int（10））， >

所有的子表都有一个 uid 值，外键约束指向 user.uid ，并设置为 ON DELETE CASCADE 和 ON UPDATE CASCADE 。

当我从 user 删除一个用户时，所有的子约束条目都被删除。但是，当我尝试更新 user.uid 值时，会导致以下错误，而不是级联 uid 更改为子表：

 ＃1452  - 无法添加或更新子行：外键约束失败`.`user_email`，CONSTRAINT`user_email_ibfk_2` FOREIGN KEY（`uid`）REFERENCES`user`（`uid`）ON DELETE CASCADE ON UPDATE CASCADE）
  

我有一种感觉，我必须在这里忽略一些明显的东西。使用 user_email 删除键约束并尝试更新 user 中的值会导致相同的错误，但会导致下一个字母 user 子表，所以我不相信这是一个表特定的错误。

编辑： p>

将结果添加到 SHOW ENGINE INNODB STATUS ：

  ------------------------ 
最新的外键错误
 ---- -------------------- 
 121018 22:35:41 Transaction：
 TRANSACTION 0 5564387，ACTIVE 0秒，进程号1619，操作系统线程id 2957499248更新或删除，在InnoDB中声明的线程499 
正在使用的mysql表1，锁定1 
 17锁结构，堆大小2496,9行锁，撤销日志条目2 
 MySQL线程ID 3435659，查询ID 24068634 localhost root更新
 UPDATE`accounts`.`user` SET`uid` ='1'WHERE`user`.`uid` = 306 
外键约束失败表`accounts`.`user_email`：
，
 CONSTRAINT`us尝试添加子表中的索引uid元组：
 DATA TUPLE：2（）; 
 
试图在子表中添加子元素：
 DATA TUPLE：2领域; 
 ... 
一串十六进制代码
 
但是在父表'accounts`.`user`中，在索引`PRIMARY`中，
与我们最接近的匹配可以找到记录：
 ... 
一串十六进制代码
  

解决方案

在一个不相关的任务上，我最近在 MySQL中引入了我们的MySQL数据库工作台，当查看上表的关系时，我注意到重复和/或虚假的关系，我以前不知何故错过了（他们没有在PHPMyAdmin FWIW中显示）。删除这些额外的关系立即解决了这个问题。

This seems to be a common error, but for the life of me I can't figure this out.

I have a set of InnoDB user tables in MySQL that are tied together via foreign key; the parent user table, and a set of child tables that store email addresses, actions, etc. These are all tied to the parent user table by a foreign key, uid, with all of the parent and child keys being int(10).

All of the child tables have a uid value with a foreign key constraint pointing to user.uid, and set to ON DELETE CASCADE and ON UPDATE CASCADE.

When I delete a user from user, all of the child constrained entries are removed. However, when I attempt to update a user.uid value, it results in the following error, rather than cascading the uid change to the child tables:

#1452 - Cannot add or update a child row: a foreign key constraint fails (`accounts`.`user_email`, CONSTRAINT `user_email_ibfk_2` FOREIGN KEY (`uid`) REFERENCES `user` (`uid`) ON DELETE CASCADE ON UPDATE CASCADE)

I have a feeling I must be missing something obvious here. Removing the key constraint with user_email and attempting to update the value in user results in the same error but for the next alphabetical user child table, so I don't believe it is a table-specific error.

EDIT:

Adding in the results from SHOW ENGINE INNODB STATUS:

------------------------
LATEST FOREIGN KEY ERROR
------------------------
121018 22:35:41 Transaction:
TRANSACTION 0 5564387, ACTIVE 0 sec, process no 1619, OS thread id 2957499248 updating or deleting, thread declared inside InnoDB 499
mysql tables in use 1, locked 1
17 lock struct(s), heap size 2496, 9 row lock(s), undo log entries 2
MySQL thread id 3435659, query id 24068634 localhost root Updating
UPDATE `accounts`.`user` SET `uid` = '1' WHERE `user`.`uid` = 306
Foreign key constraint fails for table `accounts`.`user_email`:
,
  CONSTRAINT `user_email_ibfk_2` FOREIGN KEY (`uid`) REFERENCES `user` (`uid`) ON DELETE CASCADE ON UPDATE CASCADE
Trying to add in child table, in index `uid` tuple:
DATA TUPLE: 2 fields;
...
A bunch of hex code

But in parent table `accounts`.`user`, in index `PRIMARY`,
the closest match we can find is record:
...
A bunch of hex code

解决方案

On an unrelated task, I recently brought up our MySQL database in MySQL Workbench, and when viewing the table relations for the above tables, I noticed 'duplicate' and/or spurious relations that I had somehow missed before (they weren't showing up in PHPMyAdmin FWIW). Removing these extra relations cleared up the issue immediately.

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