Question

请看一下我在MySql Workbench中写的这句话：

update customer set flag = 1
where id in (select id from customer
group by phoneNumber
having count(phoneNumber) > 1);

显示以下消息：

Error Code: 1093. You can't specify target table 'customer' for update in FROM clause

我做错了什么？

Answer 1

试试：

  update customer set flag = 1
  where id in (select * from (select id from customer
  group by phoneNumber
  having count(phoneNumber) > 1)t ) ;

Answer 2

这是另一个试图避免陷阱的变体（我使用stmt的另一个组，见下文。它可能无法反映你想要做的事情）：

update customer a
join ( select id
   from customer b
   group by id
   having count(1) > 1 
) b on a.id = b.id
    set a.flag = 1;

你的陈述select id from customer group by phoneNumber的一部分是另一个mysql的怪癖。在sql92中它是无效的，除非id在功能上依赖于phonenumber，否则它在sql99及更高版本中也是无效的。您可以通过在@@ sql_mode中设置ONLY_FULL_GROUP_BY来强制执行更严格的行为。

带子查询的MySql更新语句

2 个答案: