Question

我不知道这个问题的标题是否被理解，但我的意思是这个。

我有一张销售表，我需要“格式化”表格，添加查询一些列以指示总数，更改率（我从另一个表中获取）和以其他货币评级的总金额。

所以我的查询如下：

SELECT SalesID,SalesType,SalesDate,CurrencyType,
       case when CurrencyType = 1 then Total else 0 AS TotalOnLocalCurrency,
       case when CurrencyType = 2 then Total else 0 AS TotalOnOtherCurrency,
      (TotalOnLocalCurrency/dbo.GetCurrencyRate(SalesDate)) + TotalOnOtherCurrency) Total
FROM Sales

如果这种情况可能，我的意思是我试图这样做，但我收到了这个错误：

无效的列名称'TotalOnLocalCurrency'。

Answer 1

您可以将整个公式放在后续行中，也可以使用CROSS APPPLY：

SELECT SalesID,
       SalesType,
       SalesDate,
       CurrencyType,
       TotalOnLocalCurrency,
       TotalOnOtherCurrency,
      (TotalOnLocalCurrency/dbo.GetCurrencyRate(SalesDate)) + TotalOnOtherCurrency Total
FROM Sales
CROSS APPLY (SELECT CASE WHEN CurrencyType = 1 then Total else 0) CxA(TotalOnLocalCurrency)
CROSS APPLY (SELECT case when CurrencyType = 2 then Total else 0) CxB(TotalOnOtherCurrency)

Answer 2

您收到错误是因为您对表达式CurrencyType = 1 then Total else 0 AS TotalOnLocalCurrency设了别名。您不能在同一个select子句中引用别名列名，这违反了逻辑查询处理规则。相反，要么引用表达式本身，要么将表达式包装在表表达式中，并根据表表达式进行查询。

Answer 3

您不能使用在同一查询中引入的列别名。如果您使用的是SQL Server 2005及更高版本，我将使用CTE（公用表表达式）来处理此问题。

;WITH SalesData AS
(
    SELECT 
        SalesID, SalesType, SalesDate, CurrencyType,
        TotalOnLocalCurrency = CASE WHEN CurrencyType = 1 THEN Total ELSE 0 END,
        TotalOnOtherCurrency = CASE WHEN CurrencyType = 2 THEN Total ELSE END 
    FROM Sales
)
SELECT 
   SalesID, SalesType, SalesDate, CurrencyType,
   TotalOnLocalCurrency, TotalOnOtherCurrency,
   Total = (TotalOnLocalCurrency/dbo.GetCurrencyRate(SalesDate)) + TotalOnOtherCurrency) 
FROM  
   SalesData

Answer 4

尝试更多类似的内容：

select 
SalesID,SalesType,SalesDate,CurrencyType,
TotalOnLocalCurrency,TotalOnOtherCurrency,
TotalOnLocalCurrency/dbo.GetCurrencyRate(SalesDate)) + TotalOnOtherCurrency as total from
(
    SELECT SalesID,SalesType,SalesDate,CurrencyType,
           case when CurrencyType = 1 then Total else 0 END AS TotalOnLocalCurrency,
           case when CurrencyType = 2 then Total else 0 END AS TotalOnOtherCurrency
    FROM Sales) t

如何在SQL查询中使用计算列

4 个答案: