3

我正在使用 SQL Server 2012 并且有一个看起来像这样的值表。它填充了事件数据。

FldType Date                    Price   Size
--------------------------------------------
2       2012-08-22 00:02:01     9140    1048
0       2012-08-22 00:02:02     9140    77
1       2012-08-22 00:02:03     9150    281
2       2012-08-22 00:02:04     9140    1090
0       2012-08-22 00:02:05     9150    1
1       2012-08-22 00:02:06     9150    324
2       2012-08-22 00:02:07     9140    1063

我想跟踪 3 种字段类型 (0,1,2) 中每一种的最新值，以便最终输出如下所示。

Date                Price0  Size0   Price1  Size1   Price2  Size2
-----------------------------------------------------------------
2012-08-22 00:02:01  NULL   NULL    NULL    NULL    9140    1048
2012-08-22 00:02:02  9140   77      NULL    NULL    9140    1048
2012-08-22 00:02:03  9140   77      9150    281     9140    1048
2012-08-22 00:02:04  9140   77      9150    281     9140    1090
2012-08-22 00:02:05  9150   1       9150    281     9140    1090
2012-08-22 00:02:06  9150   1       9150    324     9140    1090
2012-08-22 00:02:07  9150   1       9150    324     9140    1063

不幸的是，它并没有忽略后续的空值，所以我得到了这个。

Date                Price0  Size0   Price1  Size1   Price2  Size2
-----------------------------------------------------------------
2012-08-22 00:02:01  NULL   NULL    NULL    NULL    9140    1048
2012-08-22 00:02:02  9140   77      NULL    NULL    NULL    NULL    
2012-08-22 00:02:03  NULL   NULL    9150    281     NULL    NULL
2012-08-22 00:02:04  NULL   NULL    NULL    NULL    9140    1090
2012-08-22 00:02:05  9150   1       NULL    NULL    NULL    NULL    
2012-08-22 00:02:06  NULL   NULL    9150    324     NULL    NULL    
2012-08-22 00:02:07  NULL   NULL    NULL    NULL    9140    1063

我当前的查询看起来像这样

SELECT [Date],
    LAST_VALUE(Price0) OVER (PARTITION BY FldType ORDER BY [Date] ) AS Price0,
    LAST_VALUE(Size0) OVER (PARTITION BY FldType ORDER BY [Date]) AS Size0,
    LAST_VALUE(Price1) OVER (PARTITION BY FldType ORDER BY [Date] ) AS Price1,
    LAST_VALUE(Size1) OVER (PARTITION BY FldType ORDER BY [Date]) AS Size1,
    LAST_VALUE(Price2) OVER (PARTITION BY FldType ORDER BY [Date] ) AS Price2,
    LAST_VALUE(Size2) OVER (PARTITION BY FldType ORDER BY [Date]) AS Size2
FROM ( 
SELECT FldType, [Date], Price, Size,
    CASE WHEN FldType = 0 THEN Price END as Price0,
    CASE WHEN FldType = 0 THEN Size END as Size0,
    CASE WHEN FldType = 1 THEN Price END as Price1,
    CASE WHEN FldType = 1 THEN Size END as Size1,
    CASE WHEN FldType = 2 THEN Price END as Price2,
    CASE WHEN FldType = 2 THEN Size END as Size2
FROM [RawData].[dbo].[Events]   
) as T1
ORDER BY [Date]

有没有办法让 SQL Server 2012 在确定最新值时忽略空值？还是有更好的方法不使用Last_Value()函数？

总而言之，我试图实现两件事。

  1. Price将and列拆分Size为 6 列（2 列 x 3 字段类型）
  2. 跟踪每列中的最新值。

任何建议都将不胜感激。

4

1 回答 1

4

我不确定你可以用 LAST_VALUE 做到这一点，除非你可能添加一个 PIVOT。

此外，您需要分别处理尺寸和价格，因为它们来自不同的行。所以，这实现了你想要的分解它。

DECLARE @source TABLE (FldType int, DateCol DateTime, Price int, Size int);

INSERT @source VALUES
    (2, '2012-08-22 00:02:01', 9140, 1048),(0, '2012-08-22 00:02:02', 9140, 77),
    (1, '2012-08-22 00:02:03', 9150, 281),(2, '2012-08-22 00:02:04', 9140, 1090),
    (0, '2012-08-22 00:02:05', 9150, 1),(1, '2012-08-22 00:02:06', 9150, 324),
    (2, '2012-08-22 00:02:07', 9140, 1063);


SELECT
    S.DateCol, Xp0.Price0, Xs0.Size0, Xp1.Price1, Xs1.Size1, Xp2.Price2, Xs2.Size2
FROM
    @source S
    OUTER APPLY
    (SELECT TOP 1 S0.Price AS Price0 FROM @source S0 WHERE S0.FldType = 0 AND S0.DateCol <= S.DateCol ORDER BY S0.DateCol DESC) Xp0
    OUTER APPLY
    (SELECT TOP 1 S1.Price AS Price1 FROM @source S1 WHERE S1.FldType = 1 AND S1.DateCol <= S.DateCol ORDER BY S1.DateCol DESC) Xp1
    OUTER APPLY
    (SELECT TOP 1 S2.Price AS Price2 FROM @source S2 WHERE S2.FldType = 2 AND S2.DateCol <= S.DateCol ORDER BY S2.DateCol DESC) Xp2
    OUTER APPLY
    (SELECT TOP 1 S0.Size AS Size0 FROM @source S0 WHERE S0.FldType = 0 AND S0.DateCol <= S.DateCol ORDER BY S0.DateCol DESC) Xs0
    OUTER APPLY
    (SELECT TOP 1 S1.Size AS Size1 FROM @source S1 WHERE S1.FldType = 1 AND S1.DateCol <= S.DateCol ORDER BY S1.DateCol DESC) Xs1
    OUTER APPLY
    (SELECT TOP 1 S2.Size AS Size2 FROM @source S2 WHERE S2.FldType = 2 AND S2.DateCol <= S.DateCol ORDER BY S2.DateCol DESC) Xs2
ORDER BY
    DateCol;

另一种方法是通过触发器或一些 ETL 维护一个单独的表，为您做摘要。

于 2013-02-19T10:26:27.340 回答