MS-Access：从 3 个表计算库存

Question

我正在从StackOverFlow 阅读this post 以调整查询以从3 个表中计算库存。我有 3 张桌子 tblItems、tblPurchase 和 tblSales。 tblItems 包含如下项目信息。

ItemCode    Description                 ItemClass   ItemCategory        ReorderLevel    Unit    Stop
IT000001    Tonner 226A                 Tonner      IT Accessories      10              Pc(s)   No
IT000002    Keyborad (A4Tech, Slim Key) Keyboard    IT Accessories      10              Pc(s)   No
IT000003    Mouse (Wireless)            Mouse       IT Accessories      10              Pc(s)   No
SI000001    A4 Size Paper               Paper       Office Stationary   10              Pc(s)   No
SI000002    Pen (Black)                 Pen         Office Stationary   10              Pc(s)   No
SI000003    Pen (Blue)                  Pen         Office Stationary   10              Pc(s)   No

我的表格的屏幕截图

tblItems：

tblPurchase：

tblSales：

我的预期结果如下所示

查询结果中的项目详细信息将来自tblItems。将每件商品的购买数量和每件商品的销售数量相加，然后从 PurchaseQuantity 中减去 SalesQuantity 以查看库存。

这是我的查询，它给了我以下警告。

SELECT DISTINCTROW tblItems.ItemCode, TblItems.Description, TblItems.ItemClass, TblItems.ItemCategory, TblPurchaseAgg.[pQuantity], TblSalesAggs.[sQuantity]
FROM (TblItems 

LEFT JOIN (SELECT TblItems.ItemCode AS ItemCode, Sum(TblPurchase.Quantity) AS pQuantity FROM TblItems LEFT JOIN TblPurchase ON TblItems.ItemCode = TblPurchase.ItemCode GROUP BY TblItems.ItemCode)  
AS TblPurchaseAgg ON TblItems.ItemCode = TblPurchaseAgg.ItemCode) 

LEFT JOIN 

(SELECT TblItems.ItemCode AS ItemCode, Sum(tblSales.Quantity) AS sQuantity FROM TblItems LEFT JOIN tblSales ON TblItems.ItemCode = tblSales.ItemCode GROUP BY TblItems.ItemCode)  AS TblSalesAggs ON TblItems.ItemCode = TblSalesAggs.ItemCode

GROUP BY TblItems.ItemCode, TblItems.Description, TblItems.ItemClass, TblItems.ItemCategory;

寻求帮助以解决警告并获得我的预期输出。任何帮助是极大的赞赏。提前致谢。

Answer 1

您不需要外部/第一组。由于您的项目表将[probably] 永远不会有重复的项目，因此返回的记录将始终是唯一的。

您使用的两个左连接都是按itemCode 分组的，因此它们也只会为每个项目返回一条记录。所以不需要整体分组。

这可能对你有用：

    SELECT 
    tblItems.ItemCode, 
    TblItems.Description, 
    TblItems.ItemClass, 
    TblItems.ItemCategory, 
    TblPurchaseAgg.pQuantity, 
    TblSalesAggs.sQuantity,
    (TblPurchaseAgg.pQuantity - TblSalesAggs.sQuantity) as stock,
    TblItems.unit
FROM 
    (TblItems 
    LEFT JOIN 
        (
            SELECT 
                TblPurchase.ItemCode AS ItemCode, 
                Sum(TblPurchase.Quantity) AS pQuantity 
            FROM
                TblPurchase
            GROUP BY TblPurchase.ItemCode
        )  AS TblPurchaseAgg
    ON TblItems.ItemCode = TblPurchaseAgg.ItemCode) 
    LEFT JOIN 
    (
        SELECT 
            tblSales.ItemCode AS ItemCode, 
            Sum(tblSales.Quantity) AS sQuantity 
        FROM 
            tblSales
        GROUP BY tblSales.ItemCode
    )  AS TblSalesAggs 
    ON TblItems.ItemCode = TblSalesAggs.ItemCode

Answer 2

你能用这个吗-

SELECT 
tblItems.ItemCode, TblItems.Description, TblItems.ItemClass, TblItems.ItemCategory, TblPurchaseAgg.[pQuantity], TblSalesAggs.[sQuantity]
FROM TblItems 

LEFT JOIN (SELECT TblPurchase.ItemCode AS ItemCode, Sum(TblPurchase.Quantity) AS pQuantity FROM TblPurchase GROUP BY TblPurchase.ItemCode)  TblPurchaseAgg ON TblItems.ItemCode = TblPurchaseAgg.ItemCode
LEFT JOIN (SELECT tblSales.ItemCode AS ItemCode, Sum(tblSales.Quantity) AS sQuantity FROM tblSales GROUP BY tblSales.ItemCode) TblSalesAggs ON TblItems.ItemCode = TblSalesAggs.ItemCode

GROUP BY TblItems.ItemCode, TblItems.Description, TblItems.ItemClass, TblItems.ItemCategory;