MYSQL each user obtains one record in three ways (group by xxx)

In MYSQL, each user reads one record in three ways (group by xxx) and asks me about the SQL statements in this regard. I remember it specially, after all, this is also quite common [SQL] select * from (select * from member_payment order by id desc) t group by member_id limit 10 first is to sort first, then group, in this way, you can obtain the most suitable data. Obvious disadvantages: Using temporary; Using filesort [SQL] select s. * from (SELECT max (id) as id FROM 'Member _ payment' group by 'Member _ id' limit 10) t left join 'Member _ payment' as s on t. id = s. id: The second type is the Union Query [SQL] select * from 'Member _ payment 'where EXISTS (select 'id' from (SELECT max ('id ') as id FROM 'Member _ payment' group by 'Member _ id' limit 10) t where t. 'id' = 'Member _ payment '. 'id') The third type is subquery stealing, which is the second type with the highest efficiency.