Question

列名ItemA，ItemB，ItemC，ItemD和ItemE

无效

我正在将其从Progress迁移到SQL，并且无法引用查询中的计算字段。在研究错误之后似乎唯一的解决方案是用完整表达式替换每个项目或创建嵌套的select语句。在这种情况下似乎都不起作用。

SELECT  
    OrderQty - (ItemE + ShippedQty) AS ItemA, 

    ((CASE WHEN (ItemA > ItemB AND ItemA > 0) 
        THEN (ItemA - ItemB) 
        ELSE 0 
    END)) AS ItemC, 

    UnitPrice * ItemC AS ItemD, 

    ((CASE WHEN OnHandQty > (ReservedQty + PickingQty) 
        THEN OnHandQty - (ReservedQty + PickingQty) 
        ELSE 0 
    END)) AS ItemB, 

    ((CASE WHEN ReservedQty > - 1 
        THEN (ReservedQty + PickedQty + PickingQty) 
        ELSE 0 
    END)) AS ItemE, 


-- Example of enumerated expression that is far to confusing to continue.
SELECT
    OrderQty - (((CASE WHEN ReservedQty > -1 THEN (ReservedQty + PickedQty + PickingQty) ELSE 0 END)) + ShippedQty),
    ((CASE WHEN (OrderQty - ((CASE WHEN ReservedQty > -1 THEN (ReservedQty + PickedQty + PickingQty) ELSE 0 END)) > 
        ((CASE WHEN OnHandQty > (ReservedQty + PickingQty) THEN OnHandQty - (ReservedQty + PickingQty) ELSE 0 END)) AND
        (OrderQty - (ItemE + ShippedQty) > 0) THEN (OrderQty - (ItemE + ShippedQty) ELSE 0 END)))), 
    UnitPrice * ((CASE WHEN (ItemA > ItemB AND ItemA > 0) THEN (ItemA - ItemB) ELSE 0 END))...

Answer 1

如果要迁移到SQL Server，可以使用CROSS APPLY子句为每个计算字段创建别名：

SELECT  
    x.ItemA,     
    t.ItemC,     
    UnitPrice * t.ItemC AS ItemD,     
    y.ItemB,     
    z.ItemE
FROM mytable
CROSS APPLY (SELECT CASE WHEN ReservedQty > - 1 
                            THEN (ReservedQty + PickedQty + PickingQty) 
                         ELSE 0 
                    END) z(ItemE)
CROSS APPLY (SELECT OrderQty - (ItemE + ShippedQty)) x(ItemA)
CROSS APPLY (SELECT CASE WHEN OnHandQty > (ReservedQty + PickingQty) 
                            THEN OnHandQty - (ReservedQty + PickingQty) 
                         ELSE 0 
                    END) y(ItemB)
CROSS APPLY (SELECT CASE WHEN (x.ItemA > y.ItemB AND x.ItemA > 0) 
                            THEN (x.ItemA - y.ItemB) 
                         ELSE 0 
                    END) AS t(ItemC)

SQLFiddle Demo

SQL查询中的计算字段

1 个答案: