SQL查询翻转值并使其成为新表中的字段

Question

我有下表

如何制作这样的输出

我使用此查询执行了上面的输出：

SELECT DISTINCT 
    C.RefVal, 
    C.CalibrationEventID, 
    C1.Result As "Trial One", 
    C2.Result AS "Trial Two", 
    C3.Result AS "Trial Three", 
    C4.Result AS "Trial Four", 
    C5.Result AS "Trial Five" 
FROM CalibrationTrials AS C 
INNER JOIN 
    (SELECT DISTINCT RefVal, Result FROM CalibrationTrials WHERE CalibrationEventID = 'CAL000001' AND RefVal = '1.0010'AND TrialNo = 1) As C1 
ON C1.RefVal = C.RefVal
INNER JOIN 
    (SELECT DISTINCT RefVal, Result FROM CalibrationTrials WHERE CalibrationEventID = 'CAL000001' AND RefVal = '1.0010'AND TrialNo = 2) As C2 
ON C2.RefVal = C.RefVal
INNER JOIN 
    (SELECT DISTINCT RefVal, Result FROM CalibrationTrials WHERE CalibrationEventID = 'CAL000001' AND RefVal = '1.0010'AND TrialNo = 3) As C3 
ON C3.RefVal = C.RefVal
INNER JOIN 
    (SELECT DISTINCT RefVal, Result FROM CalibrationTrials WHERE CalibrationEventID = 'CAL000001' AND RefVal = '1.0010'AND TrialNo = 4) As C4 
ON C4.RefVal = C.RefVal
INNER JOIN 
    (SELECT DISTINCT RefVal, Result FROM CalibrationTrials WHERE CalibrationEventID = 'CAL000001' AND RefVal = '1.0010'AND TrialNo = 5) As C5 
ON C5.RefVal = C.RefVal

WHERE C.CalibrationEventID = 'CAL000001' AND C.RefVal = '1.0010'
ORDER BY C.RefVal, C.CalibrationEventID

显然使用此查询时，输出仅固定为一个RefVal，即“1.0010”

为每个RefVal的CalibrationEventID输出image2格式的正确查询是什么？

Answer 1

以下是如何为查询使用PIVOT子句：

SELECT
  RefVal,
  CalibrationEventID,
  [1] AS [Trial One],
  [2] AS [Trial Two],
  [3] AS [Trial Three],
  [4] AS [Trial Four],
  [5] AS [Trial Five],
  [6] AS [Trial Six]
FROM CalibrationTrials
PIVOT (
  MAX(Result) FOR TrialNo IN ([1], [2], [3], [4], [5], [6])
) AS p

以上假设您的表格仅包含RefVal, CalibrationEventID, TrialNo, Result列。如果表中有更多列，则应首先分别选择这四个列，然后应用PIVOT。这里：

SELECT
  RefVal,
  CalibrationEventID,
  [1] AS [Trial One],
  [2] AS [Trial Two],
  [3] AS [Trial Three],
  [4] AS [Trial Four],
  [5] AS [Trial Five],
  [6] AS [Trial Six]
FROM (
  SELECT
    RefVal,
    CalibrationEventID,
    TrialNo,
    Result
  FROM CalibrationTrials
) AS c
PIVOT (
  MAX(Result) FOR TrialNo IN ([1], [2], [3], [4], [5], [6])
) AS p

这是必需的，因为PIVOT查询本质上是一个特殊情况GROUP BY查询。除Result之外的所有列都参与隐式分组。这就是为什么你应该摆脱那种在这种分组中不需要的东西。

这是另一种方法，没有PIVOT：

SELECT
  RefVal,
  CalibrationEventID,
  MAX(CASE TrialNo WHEN 1 THEN Result END) AS [Trial One],
  MAX(CASE TrialNo WHEN 2 THEN Result END) AS [Trial Two],
  MAX(CASE TrialNo WHEN 3 THEN Result END) AS [Trial Three],
  MAX(CASE TrialNo WHEN 4 THEN Result END) AS [Trial Four],
  MAX(CASE TrialNo WHEN 5 THEN Result END) AS [Trial Five],
  MAX(CASE TrialNo WHEN 6 THEN Result END) AS [Trial Six]
FROM CalibrationTrials
GROUP BY
  RefVal,
  CalibrationEventID