如果上一列值不为空，则更新表中的下一列

Question

当一个人收到分数时，会在表中添加一个条目@uniqueScores：

Pid | Date | Score

我有一个存储过程返回一个表 @people，其中包含来自 @uniqueScores 的数据（在过去 3 个月内）的分数列

Pid | S1 | S2 | S3 | S4 | S5

我有一个小型测试数据集，但是我无法让任何分数超出注册给用户的第一个分数以显示在 Score2 或更高版本中。

这是我的测试数据集

Pid | Date       | Score
 #1 | 2020/07/01 | 8
 #1 | 2020/09/15 | 8
 #2 | 2020/09/21 | 3
 #3 | 2020/10/01 | 5
 #4 | 2020/10/18 | 6
 #4 | 2020/10/31 | 2

我的更新语句，用数据更新 Person 列

BEGIN
  UPDATE @people
  SET    [Score5] = (CASE WHEN ( [p].[Score4] is not null and [p].[Score5] is null ) THEN [us].[Score] ELSE NULL END)
         ,[Score4] = (CASE WHEN ( [p].[Score3] is not null and [p].[Score4] is null ) THEN [us].[Score] ELSE NULL END)
         ,[Score3] = (CASE WHEN ( [p].[Score2] is not null and [p].[Score3] is null ) THEN [us].[Score] ELSE NULL END)
         ,[Score2] = (CASE WHEN ( [p].[Score1] is not null and [p].[Score2] is null ) THEN [us].[Score] ELSE NULL END)
         ,[Score1] = (CASE WHEN ( [p].[Score1] is null ) THEN [us].[Score] ELSE NULL END)
  FROM   @people [p] inner join  @uniqueScores [us]
         on [p].[PersonID] = [us].[PersonID]
  WHERE  [Date] >= @DateLimit -- within the previous 3 months
END

但是，除了第一个符合条件的值之外，查询不会更新表。返回的表是这样的

Pid | S1 | S2   | S3   | S4   | S5
#1  | 8  | null | null | null | null
#2  | 3  | null | null | null | null
#3  | 5  | null | null | null | null
#4  | 6  | null | null | null | null

不包括第一个不符合条件的表格条目，这很好，但也缺少第 4 个人的第二个分数。

我一直在查看PIVOT、WHILE 和CURSOR，但我离完成这项工作还差得远。我确定我错过了一些简单的东西，但是我看不到它。

Answer 1

UPDATE 更新每一行一次。预聚合多个更新：

UPDATE p
    SET Score1 = us.score_1,
        Score2 = us.score_2,
        Score3 = us.score_3,
        Score4 = us.score_4,
        Score5 = us.score_5
    FROM @people [p] inner join
         (SELECT us.PersonID,
                 MAX(CASE WHEN seqnum = 1 THEN Score END) as score_1,
                 MAX(CASE WHEN seqnum = 2 THEN Score END) as score_2,
                 MAX(CASE WHEN seqnum = 3 THEN Score END) as score_3,
                 MAX(CASE WHEN seqnum = 4 THEN Score END) as score_4,
                 MAX(CASE WHEN seqnum = 5 THEN Score END) as score_5
          FROM (SELECT us.*,
                       ROW_NUMBER() OVER (PARTITION BY PersonId ORDER BY Date) as seqnum
                FROM @uniqueScores us
                WHERE [Date] >= @DateLimit -- within the previous 3 months
               ) us
          GROUP BY us.PersonID
         ) s
         ON us.PersonID = p.PersonId;

注意：您无需指定分数的顺序。这会将最旧的分数放在首位。如果您想先使用较新的，请使用 ORDER BY DESC。