方法一
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)
1
| 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
|
方法二
https://blog.csdn.net/u014508939/article/details/100561133
用 GROUP_CONCAT, SUBSTRING_INDEX
1
| SELECT SUBSTRING_INDEX(GROUP_CONCAT(id, ORDER BY update_time DESC), ',', 1) FROM goods GROUP BY good_id OEDER by update_time DESC;
|
