好煩啊，讓我作android，2年沒作過了，難受182. Duplicate Emails

兩個sql  having效率高，比我本身寫的快30ms，答案更簡潔，我的習慣

我寫的：

select a.Email from (select Email,count(Email) as num from Person group by Email) as a where a.num > 1

 

答案：

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

 

我以爲答案更好，哈哈，不多用having，之後多用用，