级联删除查询

本文介绍了级联删除查询的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有三个桌子. 产品，公司，员工

I have three tables. Product, Company, Employee

ProductId是公司的forgin键 并且Company表的CompanyId是Employee的前瞻键

ProductId of Product table is foregin key for Company and CompanyId of Company table is foregin key for Employee

因此，从Product表中删除ProductId时，其他表中的所有相关记录都应删除.但是我不能碰模式(不能使用alter table).在这种情况下，我应该如何编写查询.

So on deleting ProductId from Product table, all the related records in other tables should delete. But I can't touch schema(can't use alter table). How should I write the query in that case..

推荐答案

如果您无法添加传播删除操作的约束，则必须自己编写所有必需的删除操作:

If you can't add constraints that propagates the delete, you have to write all the necessary deletes yourself:

delete employee where companyid in (select companyid from company c where productid = xxx); delete company where productid=xxx; delete product where productid=xxx;