旋转或不旋转

Posted 2023-04-12

【中文标题】旋转或不旋转

【英文标题】：Pivot or unpivot

【发布时间】：2014-03-29 01:01:21

【问题描述】：

我有一个包含每小时统计数据的表格，我需要转置（或取消转置？）

起始表的格式为：

[SystemID] [Hour] [CallStarts] [AvgDuration]  
    1         0        3           27
    1         1       10           58
    1         2       43           45
    1         3       54           63
    2         0        6           56
    2         1       46           98
    2         2       56           67
    2         3       65           77  

我需要输出是：

[SystemID] [Statistic] [Hr0] [Hr1] [Hr2] [Hr3]  
     1     CallStarts    3    10     43    54  
     1     AvgDuration  27    58     45    63
     2     CallStarts    6    46     56    65
     2     AvgDuration  56    98     67    77  

我使用的是 SQL Server 2008R2。我了解数据透视表的基础知识，但对它们没有太多经验。它的 [Statistic] 列让我不知所措。

【参考方案1】：

这是一种无需数据透视即可获得这些结果的方法，具体取决于索引和数据大小，它可能会更快：

SELECT SystemID, 
       MAX('CallStarts') AS Statistic, 
       SUM(CASE WHEN Hour = 0 THEN CallStarts ELSE 0 END) AS Hr0,
       SUM(CASE WHEN Hour = 1 THEN CallStarts ELSE 0 END) AS Hr1,
       SUM(CASE WHEN Hour = 2 THEN CallStarts ELSE 0 END) AS Hr2,
       SUM(CASE WHEN Hour = 3 THEN CallStarts ELSE 0 END) AS Hr3
FROM Table
GROUP BY SystemID
  UNION ALL
SELECT SystemID, 
       MAX('AvgDuration') AS Statistic, 
       SUM(CASE WHEN Hour = 0 THEN AvgDuration ELSE 0 END) AS Hr0,
       SUM(CASE WHEN Hour = 1 THEN AvgDuration ELSE 0 END) AS Hr1,
       SUM(CASE WHEN Hour = 2 THEN AvgDuration ELSE 0 END) AS Hr2,
       SUM(CASE WHEN Hour = 3 THEN AvgDuration ELSE 0 END) AS Hr3
FROM Table
GROUP BY SystemID
ORDER BY SystemID, Statistic ASC

【讨论】：

谢谢，这些都非常有帮助。我决定使用联合方法，因为将来由该领域的人更容易维护。性能不是问题。另外，当我一直在研究这种情况时，很明显有些数据需要额外的处理，所以我不能使用直轴。

【参考方案2】：

您可以单独查询每种类型的统计信息，然后将它们合并。我在 SQL Fiddle 上使用了 @attila 构建的相同架构。

WITH callS AS (SELECT systemid, hour, callstarts FROM t),
callD AS (SELECT systemid, hour, avgduration FROM t)

SELECT systemid, 'callStarts' AS [statistics], [0] as Hr0, [1] as Hr1, [2] as Hr2, [3] AS Hr3
FROM callS pivot (max(callStarts) FOR hour IN ([0], [1], [2], [3])) AS p

UNION ALL

SELECT systemid, 'AvgDuration' AS [statistics], [0], [1], [2], [3]
FROM callD pivot (max(avgduration) FOR hour IN ([0], [1], [2], [3])) AS p2

ORDER BY systemid, [statistics] DESC;

可以在这里看到输出：http://www.sqlfiddle.com/#!3/eb109/20/0

【参考方案3】：

您的想法是正确的……先取消旋转，然后再旋转。也许有更好的方法，但这有效：

SELECT *
FROM (
    SELECT SystemId, [Hour], [Stat], [Statistics]
    FROM
        (SELECT systemid, [hour], CallStarts, AvgDuration FROM t) nt
    UNPIVOT
        (stat FOR [Statistics] IN (CallStarts, AvgDuration)) AS ut
    ) AS ap
PIVOT
    (SUM (Stat) FOR [Hour] IN ([0], [1], [2], [3], [4])) AS p
ORDER BY [SystemId], [Statistics] DESC

这是一个显示它工作的 sqlfiddle：http://www.sqlfiddle.com/#!3/eb109/8/0

【讨论】：

谢谢，这是正确的。您可能想在末尾添加order by [systemid]。

感谢您的建议。我已经添加了订单。