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