Duplicate Emails

select email from ((select min(id) as minid,max(id) as maxid, email 
from person group by email) as newPerson) where minid != maxid

#select Email from Person group by Email having count(*)>1;
#select sum(id/id) email from person group by email

# 利用count(*)计数
select email from person group by email having count(*)>1