php - 我无法在 MySQL 中创建表

Question

这个问题已经有答案了:

Mysql error 1452 - Cannot add or update a child row: a foreign key constraint fails (21 个回答)

已关闭 7 年前。

ALTER TABLE items 
ADD CONSTRAINT member_1  
FOREIGN KEY(Member_ID)
REFERENCES users(UserID)
ON UPDATE CASCADE
ON DELETE CASCADE;

MySQL 说:

1452 - Cannot add or update a child row: a foreign key constraint fails (`shop`.`#sql-1650_234`, CONSTRAINT `member_1` FOREIGN KEY (`Member_ID`) REFERENCES `users` (`UserID`) ON DELETE CASCADE ON UPDATE CASCADE)

Answer 1

在创建新约束之前，您必须修复不正确的值:

Update items SET member_ID = null
where member_ID not in (select userID from users)