sql - #1452 - 无法添加或更新子行 : a foreign key constraint fails

Question

当我不想将两个表彼此连接时，我收到消息:#1452 - 无法添加或更新子行:外键约束失败....我想连接 oauth_uid2(主键)从使用外键 oauth_uid2 将 facebook_users 标签添加到 bugs 标签。但我总是收到这条消息。我已经清除了我的数据，但没有任何效果。在 users_facebook 表中我也有 1 条记录。

1452 - Cannot add or update a child row: a foreign key constraint fails (phples.bugs, CONSTRAINT bugs_ibfk_1 FOREIGN KEY (oauth_uid2) REFERENCES users_facebook (oauth_uid2) ON DELETE CASCADE ON UPDATE CASCADE)

错误表:FK = oauth_uid2, PK= bug_id

 #Name  Type    Collation   Attributes  Null    Default Extra   Action
     1  bug_id  int(30)         No  None    AUTO_INCREMENT    Change      Drop    Browse distinct values     Primary      Unique      Index  Spatial     Fulltext
     2  bugtitle    varchar(50) utf8_unicode_ci     No  None          Change      Drop    Browse distinct values      Primary     Unique      Index  Spatial     Fulltext
     3  bugdescription  varchar(500)    utf8_unicode_ci     No  None          Change      Drop    Browse distinct values      Primary     Unique      Index  Spatial     Fulltext
     4  oauth_uid2  int(30)         No  None          Change      Drop    Browse distinct values      Primary     Unique      Index  Spatial     Fulltext

users_facebook 表:PK= oauth_uid2

#   Name    Type    Collation   Attributes  Null    Default Extra   Action
     1  oauth_uid2  int(30)         No  None          Change      Drop    Browse distinct values     Primary      Unique      Index  Spatial     Fulltext
     2  email   varchar(70) utf8_unicode_ci     No  None          Change      Drop    Browse distinct values      Primary     Unique      Index  Spatial     Fulltext

Answer 1

您已经链接了表，这就是错误的来源。您需要确保在 users_facebook 中有记录 BEFORE 您尝试使用相同的 oauth_uid2 将记录插入 bugs，例如

users_facebook has records with oauth_uid2 `10`, `20`, `30`

你尝试在 bugs 中插入一条记录

INSERT INTO bugs (oauth_uid2) VALUES (10) // works, there's a matching record in users_facebook
INSERT INTO bugs (oauth_uid2) VALUES (15) // fails, there's no user with that id.