Duplicate Emails

Write a SQL query to find all duplicate emails in a table named Person.

+----+---------+
| Id | Email   |
+----+---------+
| 1  | a@b.com |
| 2  | c@d.com |
| 3  | a@b.com |
+----+---------+

For example, your query should return the following for the above table:

+---------+
| Email   |
+---------+
| a@b.com |
+---------+

Note: All emails are in lowercase.

查询所有重复的邮箱。

select distinct Email from Person where Id not in (select * from (select min(Id) from Person group by Email) as a) ;

872 ms.

另一种方法：

SELECT Email FROM Person GROUP BY Email HAVING COUNT(*) > 1;

 954 ms.