好烦啊，让我做android，2年没做过了，难受182. Duplicate Emails

两个sql  having效率高，比我自己写的快30ms，答案更简洁，个人习惯

我写的：

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

我觉得答案更好，哈哈，很少用having，以后多用用，