如何从每组MySql中选择前N条记录

本文介绍了如何从每组MySql中选择前N条记录的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个表，我想从该列的sub_category_id列中的每个组中获取前N个项目. 如果我设置N=10，那么将从每个组中选择前10行，或者如果我设置N=5，则将从每个组中选择前5行.请帮助我.

I have a table where i want to get top N items from each group on the base of column sub_category_id. If i set N=10 that would select first 10 rows from each group or if i set N=5 then that would select top `5 rows from each group. Please help me.

推荐答案

有多种方法可以做到这一点.这是使用相关子查询的一个:

There are multiple ways to do this. Here is one using a correlated subquery:

select t.* from t where (select count(*) from t t2 where t2.sub_category_id = t.sub_category_id and t2.id <= t.id ) <= 10;