mysql - 更改表时出现异常

Question

我在尝试更改表时遇到以下异常:

An exception occurred while executing 'ALTER TABLE instagram_picture_tag ADD CONSTRAINT FK_67B371CDBAD26311 FOREIGN KEY (tag_id) REFERENCES instagram_tag (id) ON DELETE CASCADE':            

  SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`Shopious`.`#sql-2e38_dd33a`, CONSTRAINT `FK_67B371CDBAD26311` FOREIGN KEY (`tag_id`)   
  REFERENCES `instagram_tag` (`id`) ON DELETE CASCADE)   

我该如何解决这样的问题？我试图在一个已经存在的现有表上添加约束，但它似乎与外键冲突

Answer 1

这个错误意味着对外键运行的检查失败并且无法更新表所以检查你的外键