在删除之前获取字段值

Question

我有两个表关系（层次结构）和附件，它们有关系。

delete  from category where lft between @left and @right; 

我想删除与这些类别相关的附件！

我该怎么办？

Answer 1

我建议在InnoDB MySQl and Foreign key constraints中使用FOREIGN KEYS，并为与类别和附件表相关的键定义ON DELETE - CASCADE选项。

第二个只是DELETE FROM attachments WHERE category_id BETWEEEN @left AND @right;

Answer 2

尝试：

delete c,a category c 
 join attachment a on c.id=a.category_id 
 where c.lft between @left and @right