目录

题目

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

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

Note: All emails are in lowercase.

解题思路

题目需要从Person表中找出重复出现的Email。

解题方法也很简单：按照Email分组，然后找出id出现次数超过1的Email，即使用group by 和 having 实现。

AC SQL

select Email from Person group by Email having count(id) > 1;