sql easy

    182. 查找重复的电子邮箱

    思路一

    1. SELECT Email FROM Person GROUP BY Email HAVING count(*) != 1;

    思路二

    select distinct e1.email
from person e1, person e2
where e1.email = e2.email and e1.id != e2.id;

或

select distinct e1.email
from person e1 inner join person e2
on e1.email = e2.email and e1.id != e2.id;

    这种思路其实和 180. Consecutive Numbers 的思路一样.