php - MySQL 无法使用 FK 约束进行 INSERT

Question

当我尝试插入一些数据时收到以下错误消息:

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (database/UserDetails, CONSTRAINT UserDetails_ibfk_6 FOREIGN KEY (HearAboutID) REFERENCES UserDetails (HearAboutID) ON DELETE CASCADE ON UPDATE CASCADE)

FK 关系如下所示:

我试图输入到 UserDetails.HearAboutID 中的数据存在于 UserHearAbout.UserHearAboutID 中...那么为什么它不会呢？ :(

Answer 1

来自您发布的错误

FOREIGN KEY (HearAboutID) REFERENCES UserDetails (HearAboutID) ON DELETE CASCADE ON UPDATE CASCADE)

(你实际上创建了一个引用相同表和相同列的约束)， 我猜你的 FK 约束定义是错误的(应该是

 FOREIGN KEY (HearAboutID) REFERENCES UserHearAbout (UserHearAboutID)
ON DELETE CASCADE ON UPDATE CASCADE)