182-sql.md

182. duplicate-emails 查找重复的电子邮箱

难度: Easy

刷题内容

原题连接

• https://leetcode.com/problems/duplicate-emails
• https://leetcode-cn.com/problems/duplicate-emails/description

内容描述

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。

解题方案

思路 1

官方答案

select Email from
(
  select Email, count(Email) as num 
  from Person 
  group by Email
) 
as statistic
where num>1

思路 2

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