182. 查找重复的电子邮箱

English Version

题目描述

编写一个 SQL 查询，查找 Person 表中所有重复的电子邮箱。

示例：

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

根据以上输入，你的查询应返回以下结果：

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

说明：所有电子邮箱都是小写字母。

解法

SQL

select Email from Person group by Email having count(Email) > 1

# Write your MySQL query statement below
SELECT DISTINCT
	p1.email AS "Email" 
FROM
	person AS p1
	JOIN person AS p2 ON p1.id != p2.id 
	AND p1.email = p2.email