Write a SQL query to find all duplicate emails in a table named Person.

+----+---------+
| Id | Email   |
+----+---------+
| 1  | [email protected] |
| 2  | [email protected] |
| 3  | [email protected] |
+----+---------+

For example, your query should return the following for the above table:

+---------+
| Email   |
+---------+
| [email protected] |
+---------+

GROUP BY column_name : 컬럼 네임에 맞게 그루핑 해준다.

이메일을 Group by로 정렬하고 안의 내용을 세어주자.

Solution

Select Email from Person Group by Email having count(Email) > 1;