Question

我的查询中有一个选择列表，如下所示：

SELECT 
    COUNT(*) OVER () AS TotalRowsFound,
    MIN(t.Title) AS Title,
    t.ItemID, ' + @selectedColumn + ' as SelectedColumnSales ' + ', 
    t.CurrentPrice,
    (t.CurrentPrice * t.SelectedColumnSales) as TotalRevenuePerItem
FROM 
    dbo.SearchedUserItems t

我遇到问题的查询部分如下：

  (t.CurrentPrice * t.SelectedColumnSales) as TotalRevenuePerItem

在选择列表中...根据我传递给查询的内容，“ SelectedColumnSales”可以是不同的列，如下所示：

DECLARE @selectedColumn NVARCHAR(500)

    IF(@SelectedRange=7)
       SET @selectedColumn = 't.SevenDaySales'
    ELSE IF (@SelectedRange=14)
       SET @selectedColumn='t.FourteenDaySales'
    ELSE IF (@SelectedRange=21)
       SET @selectedColumn='t.TwentyOneDaySales'
    ELSE IF (@SelectedRange=30)
       SET @selectedColumn='t.ThirtyDaySales'

现在要获得每件商品的收入列，我需要像上面那样将这两者相乘，但是查询会引发此错误：

内部异常：SqlException：无效的列名'SelectedColumnSales'。

如何在选择列表中将动态列与静态列相乘？

有人可以帮我吗？

Answer 1

如果您要编写一个动态查询，看起来就像是，只需将变量放在等式中

 declare @sql nvarchar(max)
 set @sql = 'select 
    COUNT(*) OVER () AS TotalRowsFound,
        MIN(t.Title) AS Title
        , t.ItemID
        ,' + @selectedColumn + ' as SelectedColumnSales ' + 
        ', t.CurrentPrice
         , (t.CurrentPrice * ' + @selectedColumn + ') as TotalRevenuePerItem

    FROM 
        dbo.SearchedUserItems t'
exec(@sql)

Answer 2

也许通过用户选择的索引并使用CHOOSE()

我们假设：

Item               Index
SevenDaySales      0
FourteenDaySales   1
TwentyOneDaySales  2
ThirtyDaySales     3

那么你可以

SELECT COUNT(*) OVER () AS TotalRowsFound
      ,MIN(t.Title) AS Title
      ,t.ItemID
      ,choose(@Index+1,t.SevenDaySales,t.FourteenDaySales,t.TwentyOneDaySales,t.ThirtyDaySales) as SelectedColumnSales  
      ,t.CurrentPrice
      ,(t.CurrentPrice * choose(@Index+1,t.SevenDaySales,t.FourteenDaySales,t.TwentyOneDaySales,t.ThirtyDaySales)) as TotalRevenuePerItem
 FROM  dbo.SearchedUserItems t

如果您不想传递索引，而不想传递@Index+1，则可以@SelectedRange/7

Answer 3

您可以尝试使用case子句

直接在查询中使用登录名来代替字符串concat

 SELECT 
    COUNT(*) OVER () AS TotalRowsFound,
        MIN(t.Title) AS Title
        , t.ItemID
        , case when @SelectedRange=7 then t.SevenDaySales 
              when @SelectedRange=14 then t.FourteenDaySales
              when @SelectedRange=21 then t.TwentyOneDaySales
              when (@SelectedRange=30 then t.ThirtyDaySales end 
         as SelectedColumnSales  
        , t.CurrentPrice
         , (t.CurrentPrice * t.SelectedColumnSales) as TotalRevenuePerItem

    FROM 
        dbo.SearchedUserItems t

Answer 4

将查询包装在派生表中，然后可以引用它之外的那些列：

select dt.TotalRowsFound, dt.Title, ... ,
      (dt.CurrentPrice * dt.SelectedColumnSales) as TotalRevenuePerItem
from
(
  SELECT 
    COUNT(*) OVER () AS TotalRowsFound,
        MIN(t.Title) AS Title
        , t.ItemID
        ,' + @selectedColumn + ' as SelectedColumnSales ' + 
        ', t.CurrentPrice
    FROM 
        dbo.SearchedUserItems t
) dt

SQL Server：在选择列表中用别名乘以列

4 个答案: