Question

我有这样的Sql Server查询：

Select       * 
             ,Cast(Column1 as float) as Column1Convert
             ,Cast(Column2 as float) as Column2Convert
             ,Column1Convert/Colun2Convert AS [Result] 
From         MyTable 
Order By     Points DESC, Result ASC

但我收到错误：＆＃34;列名无效＆＃39; Column1Convert＆＃39;。＆＃34;和第二个错误：＆＃34;列名无效＆＃39; Column2Convert＆＃39;。＆＃34;

你能告诉我我做错了什么吗？

Answer 1

这是因为您在查询的同一级别使用别名，这是不允许的。尝试：

Select       * 
             ,Cast(Column1 as float) as Column1Convert
             ,Cast(Column2 as float) as Column2Convert
             ,Cast(Column1 as float)/Cast(Column2 as float) AS [Result] 
From         MyTable 
Order By     Points DESC, Result ASC

Answer 2

试试这个：

SELECT
    Points, Result, Column1Convert, Column2Convert, 
    Column1Convert/Colun2Convert AS [Result]
FROM
(
    Select       * 
                 ,Cast(Column1 as float) as Column1Convert
                 ,Cast(Column2 as float) as Column2Convert
    From         MyTable 
)
Order By    
    Points DESC, 
    (Column1Convert/Colun2Convert) ASC

Answer 3

在SQL Server中，还有另一种方法可以访问字段别名以供重用（除了嵌套查询）

SELECT
      Points
    , ca.Column1Convert
    , ca.Column2Convert
    , ca.Column1Convert / ca.Colun2Convert AS [Result]
FROM MyTable
      CROSS APPLY (
                  SELECT
                        CAST(Column1 AS float) AS Column1Convert
                      , CAST(Column2 AS float) AS Column2Convert
            ) AS ca
ORDER BY
      Points DESC
      , [Result] ASC

如果您可以使用，则可能需要使用TRY_CAST（）而不是CAST（）

通过在Sql Server中划分两个数字来排序查询

3 个答案: