Problem:
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] |
+---------+

Note: All emails are in lowercase.

Solution: 根据题意,SQL语句如下:

1
2
select distinct(p.Email)
from Person p, Person q where p.Id!=q.Id and p.Email=q.Email;