SQL 计算分组依据的百分比

Question

我有一个 SQL 查询用作报告的基础。该报告显示按年、月和燃料类型分组的燃料使用量。我想计算每种燃料类型占总数的百分比，但我运气不佳。为了计算整体的百分比，我需要能够获得使用的燃料总量，而不管它属于哪个组，我似乎无法弄清楚如何做到这一点。这是我的查询：

SELECT Year([DT1].[TransactionDate]) AS [Year], Month([DT1].[TransactionDate]) AS [Month], DT1.FuelType, Format(Sum(DT1.Used),"#.0") AS [Total Used],    
FROM (SELECT TransactionDate, FuelType, Round([MeterAfter]-[MeterBefore],2) AS Used FROM FuelLog)  AS DT1
WHERE (((DT1.TransactionDate) Between [Start Date] And [End Date]))
GROUP BY Year([DT1].[TransactionDate]), Month([DT1].[TransactionDate]), DT1.FuelType
ORDER BY Year([DT1].[TransactionDate]), Month(DT1.TransactionDate), DT1.FuelType;

我尝试将以下内容添加为子查询，但我收到一条错误消息，指出子查询 returns 不止一个结果。

(SELECT Sum(Round([MeterAfter]-[MeterBefore],2)) AS Test
FROM Fuellog 
WHERE Year([Year]) and Month([Month])
GROUP BY Year([TransactionDate]), Month([TransactionDate]))

一旦我得到所有燃料的总量，我需要将使用的燃料量除以两种燃料类型的总量。我应该以不同的方式处理这个问题吗？

Answer 1

您需要加入总数 -- 像这样（未经测试可能有拼写错误）

SELECT 
  Year([DT1].[TransactionDate]) AS [Year],
  Month([DT1].[TransactionDate]) AS [Month], 
  DT1.FuelType, 
  Format(Sum(DT1.Used),"#.0") AS [Total Used],    
  (Sum(DT1.Used) / FT.Total) * 100 AS Percent
FROM (
  SELECT 
    TransactionDate,
    FuelType, 
    Round([MeterAfter]-[MeterBefore],2) AS Used 
  FROM FuelLog
)  AS DT1
JOIN (
  SELECT
     Sum(Round([MeterAfter]-[MeterBefore],2)) AS Total
     FuelType
  FROM Fuellog 
  WHERE TransactionDate Between [Start Date] And [End Date]
  GROUP BY FuelType  
) FT ON DT1.FuelType = FT.FeulType
WHERE DT1.TransactionDate Between [Start Date] And [End Date]
GROUP BY Year([DT1].[TransactionDate]), Month([DT1].[TransactionDate]), DT1.FuelType, FT.Total
ORDER BY Year([DT1].[TransactionDate]), Month(DT1.TransactionDate), DT1.FuelType, FT.Total;

Answer 2

试试这个

SELECT A.[Year]
      ,A.[Month]
      ,A.[FuelType]
      ,A.[Total Used]
      ,(A.[Total Used] / B.[Total By Year Month]) * 100 AS Percentage
  FROM
(
  SELECT Year([DT1].[TransactionDate]) AS [Year]
     , Month([DT1].[TransactionDate]) AS [Month]
     , DT1.FuelType
     , Format(Sum(DT1.Used),"#.0") AS [Total Used]
  FROM (
         SELECT TransactionDate
              , FuelType
              , Round([MeterAfter]-[MeterBefore],2) AS Used 
           FROM FuelLog
       )  AS DT1
WHERE (((DT1.TransactionDate) Between [Start Date] And [End Date]))
GROUP BY Year([DT1].[TransactionDate]), Month([DT1].[TransactionDate]),     DT1.FuelType
ORDER BY Year([DT1].[TransactionDate]), Month(DT1.TransactionDate),     DT1.FuelType
  ) A
INNER JOIN 
  (
    SELECT Sum(Round([MeterAfter]-[MeterBefore],2)) AS [Total By Year Month]
         , Year([TransactionDate]) AS [Year]
         , Month([TransactionDate])) AS [Month]
      FROM Fuellog 
     GROUP
        BY Year([TransactionDate])
         , Month([TransactionDate]))
  ) B
   ON A.[Year] = B.[Year]
  AND A.[Month] = B.[Month]

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ms-access-2013