Question

Balance列显示当前现有库存+未结采购数量减去已输入数量。

我在SELECT语句中有ALIASes的现有查询：

SELECT dbo.Items.ItemNo, 
       dbo.Items.Name, 
       dbo.Vendors.Name AS VendorName, 
       ISNULL(ItemsStock.StockOnHand, 0) AS [Stock on Hand], 
       ISNULL(PO.[Open PO's'], 0) AS [Open PO], 
       ISNULL(WO.OpenWOQTY, 0) AS [QTY Entered].

如何添加一个名为Balance的额外列来累计库存和打开采购订单，然后扣除已输入的数量？

Answer 1

SELECT dbo.Items.ItemNo, 
       dbo.Items.Name, 
       dbo.Vendors.Name AS VendorName, 
       ISNULL(ItemsStock.StockOnHand, 0) AS [Stock on Hand], 
       ISNULL(PO.[Open PO's'], 0) AS [Open PO], 
       ISNULL(WO.OpenWOQTY, 0) AS [QTY Entered],
       ISNULL(ItemsStock.StockOnHand, 0) + ISNULL(PO.[Open PO's'], 0) - ISNULL(WO.OpenWOQTY, 0) AS [Balance]
FROM table

Answer 2

三点建议：

使用表别名。
使用coalesce()代替isnull()。 coalesce()是ANSI标准。
使用不需要转义的列名称。

这看起来像：

SELECT i.ItemNo, i.Name, v.Name AS VendorName, 
       COALESCE(is.StockOnHand, 0) AS Stock_on_Hand, 
       COALESCE(PO.[Open PO's'], 0) AS Open_PO, 
       COALESCE(WO.OpenWOQTY, 0) AS QTY_Entered,
       (COALESCE(is.StockOnHand, 0) + COALESCE(PO.[Open PO's'], 0) - COALESCE(WO.OpenWOQTY, 0) as Balance
FROM dbo.Items i JOIN
     dbo.Vendors v
     . . .

如果您不想重复别名，传统方法是使用CTE或子查询。 SQL Server还提供了横向连接，引入了apply关键字：

SELECT i.ItemNo, i.Name, v.Name AS VendorName, 
       vals.Stock_on_Hand, vals.Open_PO, vals.QTY_Entered,
       (vals.Stock_on_Hand + vals.Open_PO - vals.QTY_Entered) as Balance
FROM dbo.Items i JOIN
     dbo.Vendors v
     . . . CROSS APPLY
     (VALUES ( COALESCE(is.StockOnHand, 0), COALESCE(PO.[Open PO's'], COALESCE(WO.OpenWOQTY, 0))
     ) vals(Stock_on_Hand, Open_PO, QTY_Entered);

SQL Server中2个别名的SUM

2 个答案: