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我正在尝试计算数据库中总损失的机器时间。表中的列是 MachineID aka PlantID、StartTime、EndTime。

从理论上讲，它只需按 machineID 和 StartTime 对表进行排序，然后取当前行的 StartTime 并减去前一行 EndTime。

这是我当前有效的查询：

SELECT SUM([StartTime] - [EndTime]) AS TotalLostTime  
FROM(SELECT * 
     FROM (SELECT ROW_NUMBER() OVER (ORDER BY [PlantID], [StartTime]) AS [Row],
                  [MachineRecords].PlantID , [MachineRecords].EndTime 
           FROM [MachineRecords]) AS a 
     JOIN (SELECT * 
           FROM (SELECT ROW_NUMBER() OVER (ORDER BY [PlantID], 
                                                        [StartTime]) AS [Row1],
                        [MachineRecords].PlantID as PlantID1 , 
                        [MachineRecords].StartTime 
                 FROM [MachineRecords]) as b) m 
     ON m.PlantID1 = a.[PlantID] 
        AND a.[Row] = m.[Row1]-1) lostTimeQuery

我的问题是：是否有更好（更简洁）的方法来实现此查询的相同结果？

谢谢您的帮助。

编辑：

在 Wildplasser 发表评论后，我创建了这个查询：

SELECT SUM(a.StartTime - a.LagEnd) as LostTime 
FROM (SELECT [PlantID], [StartTime], [EndTime], 
             LAG([PlantID]) OVER (ORDER BY PlantID, StartTime) LagPlantID,
             LAG([EndTime]) OVER (ORDER BY PlantID, StartTime) LagEnd 
      FROM MachineRecords) a 
WHERE a.PlantID = a.LagPlantID
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1 回答 1

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这是我使用的结果查询:)

SELECT SUM(a.StartTime - a.LagEnd) as LostTime 
FROM (SELECT [PlantID], [StartTime], [EndTime], 
             LAG([PlantID]) OVER (ORDER BY PlantID, StartTime) LagPlantID,
             LAG([EndTime]) OVER (ORDER BY PlantID, StartTime) LagEnd 
      FROM MachineRecords) a 
WHERE a.PlantID = a.LagPlantID
于 2012-12-06T01:15:35.397 回答