解决You can‘t specify target table ... for update in FROM clause

问题来源:LeetCode196. Delete Duplicate Emails。 一开始我写的SQL代码是:

delete from Person where (email, id) not in
(select email, min(id) minId from Person group by email)

结果报错:Runtime Error
You can’t specify target table ‘Person’ for update in FROM clause

谷歌了一下,从StackOverflow You can’t specify target table for update in FROM clause 得到了答案:
The problem is that MySQL, for whatever inane reason, doesn’t allow you to write queries like this:

UPDATE myTable SET myTable.A =
(
    SELECT ... FROM myTable...
)

That is, if you’re doing an UPDATE/INSERT/DELETE on a table, you can’t reference that table in an inner query.
The solution is to replace the instance of myTable in the sub-query with (SELECT * FROM myTable), like this:

UPDATE myTable SET myTable.A =
(
    SELECT ... FROM (SELECT * FROM myTable) AS something ...
)

所以本题,把子查询中的Person改为(select * from Person) P, 就AC了:

delete from Person where (email, id) not in
(select email, min(id) minId from (select * from Person) P group by email)

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转载自blog.csdn.net/qq_23204557/article/details/129222971