Question

我正在尝试通过使用MS SQL表创建的列的值执行一些加法，乘法和减法来创建新列。在下面的代码中，我创建了[PremiumByCodes] col。通过计算。同样，当我尝试创建col。 [佣金]，它显示了我，无效的列名“PremiumBYCodes”。我还想对Deduction列进行相同类型的乘法并创建一个新列。有关如何继续这样做的任何建议吗？

     select 

     [PremiumByCodes]  = a.[NWP]/(1-c.[Commission%]-c.[Deduction%]),    

     [Commission] = [PremiumByCodes] /c.[Commission%], 

     [Deduction] = [PremiumByCodes] /c.[Deduction%],

Answer 1

这看起来像SQL Server代码。

首先，数据库不允许在定义它们的同一SELECT中重用列别名。通常的方法是使用子查询或CTE。另一种方法使用横向连接，使用APPLY：

在SQL Server中实现

select v.PremiumByCodes, v.PremiumByCodes / c.[Commission%] as Commission,
       v.PremiumByCodes /c.[Deduction%] as Deduction, 
       . . .
from . . . outer apply
     (values (a.[BHSINWP]/(1-c.[Commission%]-c.[Deduction%]) )) v(PremiumByCodes)
. . .

Answer 2

在sql-server中，除了查询的order by之外，您不能通过别名引用列。

select 
    [PremiumByCodes] = a.[BHSINWP]/(1-c.[Commission%]-c.[Deduction%])
  , [Commission] = (a.[BHSINWP]/(1-c.[Commission%]-c.[Deduction%]))/c.[Commission%]
  , [Deduction]  = (a.[BHSINWP]/(1-c.[Commission%]-c.[Deduction%]))/c.[Deduction%]

使用动态创建的列会提示“无效列”错误

2 个答案: