使用案例和按聚合分组的 SQL 查询答案

【问题标题】：SQL query using case and Group by aggregation使用案例和按聚合分组的 SQL 查询
【发布时间】：2015-08-07 21:09:17
【问题描述】：

我有以下情况：

我拥有的仓库的 1 个表：ProductID、数量和地址我拥有的商店的 1 表：ProductID 和数量 Stores 存储地址的 1 个表

我需要知道的是产品是“有货”还是“缺货”，使用的标准是产品必须有数量 >=0 或 >20k 才能被视为“缺货”两个表（商店和仓库）

我尝试过的如下：

SELECT Product_Cod, qty_wh, QtyStore,
    CASE
        WHEN sum(QtyStore) BETWEEN 1 AND 20000 THEN 
                                CASE
                                        WHEN qty_wh > 0 THEN 'In Stock'
                                        WHEN qty_wh = 0 THEN 'In Stock'
                                END
        WHEN sum(QtyStore) = 0 OR sum(QtyStore) > 20000 THEN
                                CASE
                                        WHEN qty_wh <= 0 THEN 'Out of Stock'
                                        WHEN qty_wh > 0 THEN 'in Stock'
                                END
    END AS [Result]
FROM tb_Products, tb_qtyStock, tb_StoreProdAddress
WHERE Product_Cod = wh_CodProduct
AND Product_Cod = Store_CodProduct
GROUP BY Product_Cod, qty_wh, QtyStore 
ORDER BY Product_Cod

哪些输出：

   ProdCod qty_wh QtyStore   Result
    10026   26      0       In Stock
    10026   26      1       In Stock
    10026   26      2       In Stock
    10070   25      0       In Stock
    10070   25      2       In Stock
    10070   25      3       In Stock
    10071   20      0       In Stock
    10071   20      1       In Stock
    10071   20      29991   In Stock
    10072   32      0       In Stock
    10072   32      1       In Stock
    10072   32      29978   In Stock
    10204   0       0       Out of Stock
    10204   0       1       In Stock
    10204   0       4       In Stock
    10204   0       29996   Out of Stock

但我不能让它像我想要的那样工作，因为 QtyStore 列不 SUM() 它重复，因为 tb_StoreProdAddress 用于多个商店，因此多个商店可以拥有相同的产品，但每个商店可能有该产品的不同地址，但仓库中给定产品的地址是相同的。

有一种方法可以对 QtyStore 列进行 SUM() 并将 qty_wh 分组？？？

【问题讨论】：

你不能使用 sum 的原因是它在 group by 子句中。您是否尝试过将 QtyStore 列从 group by 子句中取出？

标签： sql sql-server

【解决方案1】：

您可以尝试最大化 qty_wth，然后像这样对 QtyStore 求和：

SELECT Product_Cod, max(qty_wh) as qty_wh, sum(QtyStore) as QtyStore,
    CASE
        WHEN sum(QtyStore) BETWEEN 1 AND 20000 THEN 
                            CASE
                                    WHEN qty_wh > 0 THEN 'In Stock'
                                    WHEN qty_wh = 0 THEN 'In Stock'
                            END
        WHEN sum(QtyStore) = 0 OR sum(QtyStore) > 20000 THEN
                            CASE
                                    WHEN qty_wh <= 0 THEN 'Out of Stock'
                                    WHEN qty_wh > 0 THEN 'in Stock'
                            END
END AS [Result]
FROM tb_Products, tb_qtyStock, tb_StoreProdAddress
WHERE Product_Cod = wh_CodProduct
AND Product_Cod = Store_CodProduct
GROUP BY Product_Cod
ORDER BY Product_Cod

【讨论】：

【解决方案2】：

为避免多次执行相同的操作，您可以在子查询中进行计算：

SELECT Product_Cod,
       qty_wh,
       QtyStore,
       CASE
          WHEN QtyStore BETWEEN 1 AND 20000
          THEN
             CASE
                WHEN qty_wh > 0 THEN 'In Stock'
                WHEN qty_wh = 0 THEN 'In Stock'
             END
          WHEN QtyStore = 0 OR QtyStore > 20000
          THEN
             CASE
                WHEN qty_wh <= 0 THEN 'Out of Stock'
                WHEN qty_wh > 0 THEN 'in Stock'
             END
       END AS [Result]
    FROM (SELECT Product_Cod,
               MAX (qty_wh) AS qty_wh,
               SUM (QtyStore) AS QtyStore,
               FROM tb_Products,
               tb_qtyStock,
               tb_StoreProdAddress 
             WHERE Product_Cod = wh_CodProduct
             AND Product_Cod = Store_CodProduct
             GROUP BY Product_Cod)
    ORDER BY Product_Cod

希望对你有帮助。

【讨论】：

【解决方案3】：

只需从 GROUP BY 子句中删除 QtyStore 列，然后将 SUM(QtyStore) 放入查询的 SELECT 部分。

SELECT Product_Cod, qty_wh, SUM(QtyStore) AS TotalQtyStore,
    CASE
        WHEN sum(QtyStore) BETWEEN 1 AND 20000 THEN 
                                CASE
                                        WHEN qty_wh > 0 THEN 'In Stock'
                                        WHEN qty_wh = 0 THEN 'In Stock'
                                END
        WHEN sum(QtyStore) = 0 OR sum(QtyStore) > 20000 THEN
                                CASE
                                        WHEN qty_wh <= 0 THEN 'Out of Stock'
                                        WHEN qty_wh > 0 THEN 'in Stock'
                                END
    END AS [Result]
FROM tb_Products, tb_qtyStock, tb_StoreProdAddress
WHERE Product_Cod = wh_CodProduct
AND Product_Cod = Store_CodProduct
GROUP BY Product_Cod, qty_wh
ORDER BY Product_Cod

【讨论】：

谢谢丹！我很确定我昨天尝试过，但在某个地方搞砸了，因为实际的查询有更多的方法，这是它的简短版本，但现在它就像一个魅力！盲点，猜猜只是需要另一双眼睛才能看到我的错误XD