Question

我有两张桌子，并且购买它们都具有以下结构

ID, ItemID, Quantity, Date

。我想从装运中获取物品的总数量-购买

第三个表Item中的ID有一个外键，结构为

ID int auto_increment,
ItemCode VARCHAR(10) unique NOT NULL,
ItemDescription VARCHAR(50),
Price decimal(4,2) DEFAULT 0,
primary key(ID)

我曾尝试通过联接来做到这一点，但是由于某些原因，每次我都会获得更多重复数据

Answer 1

;WITH cte
     AS (SELECT SUM(s.Quantity) AS 'shipment sum',
                s.ItemId
         FROM dbo.Shipment s            
         GROUP BY s.ItemId)

     SELECT c.[shipment sum] - b.[purchase sum] AS 'total quantity',i.ItemDescription
     FROM cte AS c
          INNER JOIN
     (
         SELECT SUM(p.quantity) as'purchase sum',
                p.itemid
         FROM dbo.Purchase p            
         GROUP BY p.ItemId
     ) b ON c.itemid = b.itemid
    INNER JOIN item i ON i.id=c.itemid

Answer 2

假设您希望全天总计，按ItemCode排序

select i.ID, i.ItemCode, i.ItemDescription, i.Price, t.Quantity
from Items i
left join (
    select ItemID, sum(Quantity) Quantity
    from (
        select ItemID, Quantity
        from Shipment 
        union all 
        select ItemID, -Quantity
        from Purchase
        ) t
    group by ItemID
    ) t on t.ItemID = i.ID
order by i.ItemCode;

我想使用其他表中的SUM（）函数

2 个答案: