MYSQL每个用户取1条记录的三种写法（group by xxx）_MySQL

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MYSQL每个用户取1条记录的三种写法（group by xxx）

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

[sql]

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

[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

第二种是联合查询

[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`

)

第三种是子查询

窃以为第二种效率最高

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