mysql 多表查询先排序，然后再取分组<mysql 先order by，然后再取group by分组>

select * from (
        select cv.lasttime,cm.mailbox,cv.clientip from `co_user_visitlog` as cv INNER JOIN `core_mailbox` as cm where cv.mailbox_id = cm.mailbox_id and cm.mailbox in 
　　　　　　 (
                   'pyj@test.com','cs@test.com','cs2@test.com','cs1@test.com'
            )order by cv.lasttime desc
    　　　　) as t
    group by t.mailbox;

在一条语句里面不可以先order by 再进行group by

最终套了一个查询，然后再group by 出来