SQL |具有多个分组和条件的累积成本

| 在对该站点以及其他站点进行了大量研究之后,我尝试了此SQL语句的多种变体,但是我缺少一些东西 我的数据表如下所示:
.....Date.....Boolean...Group....Imp......Cost
....1/1/11.....TRUE.........A........High.......$100
....1/1/11.....FALSE........A........Med........$150
....1/1/11.....TRUE.........B........High.......$200
....2/1/11.....TRUE.........B........Low........$300
对于每个月,我希望按\“ Group \”和\“ Imp。\”分组的累计成本现在是我的SQL查询,但是(在我更大的数据集上)的累计总和是WAAAYYY。
SELECT t1.Date,
       t1.Group,
       t1.Imp,
       Sum(t2.Cost) AS RunTotal
FROM datatable t1
INNER JOIN datatable t2 ON t1.Date >= t2.Date
WHERE t1.Boolean=TRUE
GROUP BY t1.Date,
         t1.Group,
         t1.Imp
请注意,由于我正在使用MS Access,因此无法使用交叉联接。任何错误的想法在哪里?     
已邀请:
        您是否尝试过完全不使用Join?这是我使用的查询,它似乎正常工作。
SELECT [Date], [Group], Img, SUM(Cost) AS RunTotal
FROM datatable WHERE [Boolean] = True
GROUP BY [Date], [Group], Img
    
        如果希望按组和按展示的总运行量,则还需要在联接中包括:
Select t1.Date, t1.Group, t1.Imp, Sum(t2.Cost) as RunTotal
From datatable t1 
Inner Join datatable t2 on t1.Group = t2.Group and t1.Imp = t2.Imp and t1.Date >= t2.Date
WHERE t1.Boolean=TRUE
GROUP BY t1.Date, t1.Group, t1.Imp
现在,您将与t1.Date> = t2.Date的所有记录一起加入,因此包括不匹配组/ imp的记录。只需运行以下命令:
Select t1.Date, t1.Group, t1.Imp, t2.Date, t2.Group, t2.Imp, t2.Cost
From datatable t1 
Inner Join datatable t2 on t1.Date >= t2.Date
WHERE t1.Boolean=TRUE
您应该看到t2。总计中不需要的成本记录。     

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