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。
1 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：
1 SELECT Email FROM Person GROUP BY Email HAVING COUNT(*) > 1;
954 ms.
原文：http://www.cnblogs.com/catcoding/p/4712665.html