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mysql 分组后的组内排序

 3 years ago
source link: http://abcdxyzk.github.io/blog/2021/04/04/mysql-row_number/
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mysql 分组后的组内排序

2021-04-04 21:34:00

https://www.cnblogs.com/hxfcodelife/p/10226934.html

数据库的查询顺序是先分组的，最后才将结果进行排序。 group by XX order by yy 是不行的

用 row_number() over(partition by XX order by YY desc)

select a.Classid,a.English from (select Classid,English,row_number() over(partition by Classid order by English desc) as n from CJ) a where n<=2

https://blog.csdn.net/u014508939/article/details/100561133

用 GROUP_CONCAT, SUBSTRING_INDEX

SELECT SUBSTRING_INDEX(GROUP_CONCAT(id, ORDER BY update_time DESC), ',', 1) FROM goods GROUP BY good_id OEDER by update_time DESC;

Posted by kk

2021-04-04 21:34:00tools, mysql

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