与SQL聚合函数抗争

我有一个包含随时间变化的权重的表，我想将其作为流量进行评估：

Scan    TimeStamp       Position  Weight
01      14/11/01 12:00  0         0
01      14/11/01 12:10  10        1.6
02      14/11/01 13:00  0         2.6
02      14/11/01 13:10  10        4.2
...

现在我想计算扫描期间的流量（开始到结束）。 我的查询如下所示：

Select MeanTime, TheFlow From
(Select AVG(TheTimeStamp) as MeanTime From flow Where ScanNumber=73),
(Select Weightdiff / TimeSpan as TheFlow From
      (Select (MaxWeight - MinWeight) as WeightDiff From
           (Select Weight as MAXWEIGHT from Flow Where ScanNumber=73 HAVING "POSITION"=MAX("POSITION")),
           (Select Weight as MINWEIGHT from FLOW Where ScanNumber=73 HAVING "POSITION"=MIN("POSITION")),
      (Select (MaxTime - MinTime) * 24 as TimeSpan From
           (Select MAX("THETIMESTAMP") as MaxTime From FLOW Where ScanNumber=73),
           (Select MIN("THETIMESTAMP") as MinTime From Flow Where ScanNumber=73))));

我得到一个错误：

SQL错误代码=-104。
select列表中的表达式无效（未包含在聚合函数或GROUP BY子句中）

怎么了

为了澄清我的问题，我需要从数据中提取以下信息：

扫描开始（如12:00）和结束（如12:10）之间的平均时间（同时） e、 g.扫描编号01），即12:05

我需要终点和起点之间的重量差

我必须根据重量差和开始和结束之间的时间来计算“流量”

总之，我需要两个数据和流，我想绘制（随时间流动）

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这应该可以完成单个扫描的工作，这似乎是必需的

DECLARE @Scan INT = 1
SELECT 
    MeanTime = DATEADD(SECOND, DATEDIFF(SECOND, FirstScan.TimeStamp, LastScan.TimeStamp), FirstScan.TimeStamp)
    , WeightDifference = LastScan.Weight - FirstScan.Weight
FROM
    (SELECT Position = MIN(Position) FROM Flow WHERE Scan = @Scan) MinScan
    CROSS JOIN (SELECT Position = MAX(Position) FROM Flow WHERE Scan = @Scan) MaxScan
    INNER JOIN Flow FirstScan ON MinScan.Position = FirstScan.Position
        AND FirstScan.Scan = @Scan
    INNER JOIN Flow LastScan ON MaxScan.Position = LastScan.Position
        AND LastScan.Scan = @Scan

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“扫描时计算流量”是什么意思？你的意思是计算开始和停止之间的重量差？您能提供所需的输出吗？所需的输出应该是这样的：14/11/01 12:05 1.6和14/11/01 13:05 1.6（扫描的平均时间，结束时的重量-开始时的重量）您的数据库系统是什么？哪个版本？