如何选择最近几天评分最高的照片？

Question

这是我的数据上下文：

Photos (ID, Title)
Users (ID, FullName)
Ratings (PhotoID, UserID, Value, Date)

业务规则：

• 用户可以从 1 到 5 对照片进行评分
• 给定用户只能对给定照片评分一次

我想选择最近（比如说 3 天）内评分最高的照片。那么今天、昨天和前天哪张照片的评分最高呢？如果可能的话，我想让天数可变。我必须显示最后 N 天，只有他们评分不包括空天。

我想在单个查询/结果中获取照片，因为我想将其绑定到 ListView 以在 Web 表单上显示它们。

我是这样开始的：

DECLARE @days INT = 3

SELECT TOP (@days) ... FROM Ratings
INNER JOIN Photos ON Photos.ID = Ratings.PhotoID
GROUP BY DATEDIFF(day, [Date], CURRENT_TIMESTAMP)
ORDER BY DATEDIFF(day, [Date], CURRENT_TIMESTAMP) DESC

如何按 PhotoID 对我的组进行分组，按 SUM(Value) 排序并从每个组中选择第一个？非常感谢您的帮助。

Answer 1

SELECT Date, TotalRating, Photos.*
FROM Photos
INNER JOIN 
(SELECT ROW_NUMBER() OVER (ORDER BY Date DESC) AS RowNumber, 
        PhotoID, Date, TotalRating
 FROM (SELECT ROW_NUMBER() OVER (PARTITION BY Date, ORDER BY TotalRating DESC) AS inRowNumber,
              PhotoID, Date, TotalRating
        FROM (SELECT PhotoID, Date, SUM(Value) AS TotalRating
              FROM Photos
              GROUP BY PhotoID, Date
              HAVING SUM(Value) > 0 ) t)
 WHERE inRowNumber = 1) t ON Photos.Id = t.PhotoID
 WHERE RowNumber <= @days