Question

我有三个表：零件数据，订单数据和发货数据。尝试编写存储过程，返回部件号，名称等以及仍要装运的部件数量。

当某些订单中的某些零件已经发货时 - 我们必须从订单中订购的零件总数中减去该数量。如果尚未发出特定订单的零件 - 我们必须显示订购零件的数量。

我到目前为止尝试过：

PROCEDURE dbo.GetParts
AS
SELECT od.OrderDetailID, od.PartNr, od.OrderNr, d.PartName, RemainsToBeShipped =
CASE 
WHEN EXISTS(SELECT sh.Quantity FROM Shipped AS sh WHERE sh.OrderDetailID = od.OrderDetailID)
THEN od.Quantity - sh.Quantity
ELSE od.Quantity
END
FROM OrderDetails AS od, Parts AS d, Shipped as s
WHERE od.NrDet = d.NrDet AND od.OrderDetailID = s.OrderDetailID

这不起作用 - “ELSE”永远不会发射之后的部分。

Answer 1

SELECT
    od.OrderDetailID, od.PartNr, od.OrderNr, d.PartName
    , od.Quantity - ISNULL(s.Quantity,0) [RemainsToBeShipped]
FROM OrderDetails AS od
INNER JOIN Parts AS d ON od.NrDet = d.NrDet
LEFT JOIN Shipped as s ON od.OrderDetailID = s.OrderDetailID

Answer 2

您的加入会阻止您获取任何未发货的物品。试试这个：

SELECT od.OrderDetailID, od.PartNr, od.OrderNr, d.PartName, RemainsToBeShipped =
 od.Quantity - ISNULL(s.Quantity,0)
FROM OrderDetails AS od
INNER JOIN Parts AS d ON od.NrDet = d.NrDet 
LEFT OUTER JOIN Shipped AS s ON od.OrderDetailID = s.OrderDetailID

SQL：仅在记录存在时执行减法

2 个答案: