mysql 获取所有分类和每个分类的前几条记录 比如有文章表 article(id,category,insertdate) 现在要用sql找出每种类型中时间最新的前n个数据组成的集合 select a1.*from article as a1inner join (select a.category,a.insertdatefrom article as aleft join a
mysql 获取所有分类和每个分类的前几条记录
比如有文章表 article(id,category,insertdate)
现在要用sql找出每种类型中时间最新的前n个数据组成的集合
select a1.*from article as a1 inner join (select a.category,a.insertdate from article as a left join article as b on a.category = b.category and a.insertdate <= b.insertdate group by a.category,a.insertdate having count(b.insertdate) <= @n ) as b1on a1.category = b1.categoryand a1.insertdate = b1.insertdateorder by a1.category,a1.insertdate desc
?
ps: ?@n 就是要取多少条