【lc-database】182.查找重复的电子邮箱

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。

1.groud by + having

select email from person GROUP BY email having count(*) > 1;

2.groud by + 临时表

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