Question

SELECT 
    Item.Itemno 
    , SUM(Delivered_item.qtyordered) AS SumOfqtyordered 
    , SUM(Item_issued.qtyissued) AS SumOfqtyissued
FROM  
    Item  
    INNER JOIN Delivered_item ON Item.Itemno = Delivered_item.itemno 
    INNER JOIN Item_issued ON Item.Itemno = Item_issued.Itemno
GROUP BY  
    Item.Itemno;

这是我的sql视图。在我的数据库中，delivered_item有7条记录，而item_issued只有2条记录。当我执行SUM时，qtyissued的总数出错，1条记录（qtyissued）乘以3而另一条记录乘以4，因为delivered_item有7条记录（2个相同itemno）...如何解决这个问题...

Answer 1

您需要使用子查询：

SELECT *
FROM item i
INNER JOIN
  (SELECT itemno,
          Sum(qtyordered)
   FROM delivereditem
   GROUP BY itemno) d ON d.itemno = i.itemno
INNER JOIN
  (SELECT itemno,
          Sum(qtyissued)
   FROM itemissued
   GROUP BY itemno) iss ON iss.itemno = i.itemno

如果您认为可能需要执行此操作，请将每个子查询转换为视图并使用该子查询（保存打字时）

编辑：在子查询中添加了分组。对不起！

Microsoft访问查询设计

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