182. Duplicate Emails (Easy)

Source: https://leetcode.com/problems/duplicate-emails/#/description
Description:

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 |
+---------+

Solution:

select Email from
(
    select Email,count(*) as jishu from Person
    group by Email
)a
where jishu>1