关于MYSQL中每个用户取1条记录的三种写法(group by xxx)

时间:2022-10-29 14:42:33

今天以前的同学问我关于这方面的SQL语句,我特意记忆一下,毕竟这个也比较常见了

复制代码代码如下:


select * from (select * from member_payment 
                order by id desc) t group by member_id limit 10


第一种是先排序,然后group,这样的话自然可以取到最适合的一条数据。
缺点很明显:Using temporary; Using filesort

复制代码代码如下:


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 


第二种是联合查询 

复制代码代码如下:


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`
)


第三种是子查询
窃以为第二种效率最高