https://leetcode.com/problems/duplicate-emails/
SQL Schema
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] |
+---------+
Algorithm
没什么可说的GROUP BY & HAVING 的用法；
MySQL
select Email
from Person
group by Email
having count(Email) > 1;