文巾解题 182. 查找重复的电子邮箱

Posted 2021-08-01 刘文巾

1 题目描述

2 解题思路

2.1 HAVING语句

SELECT P.Email
FROM Person P
GROUP BY P.Email
HAVING COUNT(*)>1

2.2 嵌套SQL

SELECT Email
FROM (SELECT P.Email, COUNT(*) AS num
FROM Person P
GROUP BY P.Email
) as A
WHERE num>1