用SQL找出每种类型中时间最新的前N个数据组成的集合
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 B1 ON A1.Category = B1.Category AND A1.InsertDate = B1.InsertDate ORDER BY A1.Category,A1.InsertDate DESC
