SQL 기초(3) - group by

• leetcode 182

아래의 테이블에서 중복된 이메일 찾기

person
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| id | int |
| email | varchar |
+-------------+---------+

select email
from person
group by email
having cnt(email)>1;   

select email
from person
group by email
having cnt(*)>1;