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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
@N 就是你要取多少条
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