mysql 去除重复sql语句

Question

根据emai字段去除重复，有个附加条件是另一个字段出现频率最高的数据保留，其他的删除
数据表中有
id  email               country           
1   [email protected]            Japan           
2   [email protected]            China          
3   [email protected]            China           
4   [email protected]            Japan          
5   [email protected]            Chain           
6   [email protected]            Chain
去除重复项的结果为[email protected]            China
[email protected]            Japan          
[email protected]            Chain  重复的email   [email protected] country ，China有3次，Japan有两次，左右保留的Chain         

Answer 1

Japan有两次,不是就只有1次的嘛

Answer 2

select email,country   
from tb
group by  email,country   

Answer 3

select * from (
SELECT email,country,count(*) as gs from [long] group by email,country) a
where not exists(select 1 from (SELECT email,country,count(*) as gs from [long] group by email,country) a1 where a.email=a1.email and a.gs<a1.gs)

Answer 4

select distinct email,country  
from 数据表