LeetCode Delete Duplicate Emails，leetcodeduplicate

LeetCode Delete Duplicate Emails，leetcodeduplicate

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id.

+----+------------------+| Id | Email            |+----+------------------+| 1  | john@example.com || 2  | bob@example.com  || 3  | john@example.com |+----+------------------+Id is the primary key column for this table.

For example, after running your query, the above Person table should have the following rows:

+----+------------------+| Id | Email            |+----+------------------+| 1  | john@example.com || 2  | bob@example.com  |+----+------------------+

如果這樣寫會有錯：

delete from Person where id not in (select max(a.id) as id from Person a group by email);

Runtime Error Message:	You can't specify target table 'Person' for update in FROM clause
Last executed input:	{"headers": {"Person": ["Id", "Email"]}, "rows": {"Person": []}}

AC：

delete from Person where id not in (select id as id from (select min(b.id) as id from Person b group by email) as a);