如何对 MS-SQL Server 中的别名列执行 GROUP BY? [英] How do I perform a GROUP BY on an aliased column in MS-SQL Server?

问题描述

我正在尝试对别名列(下面的示例)执行 group by 操作，但无法确定正确的语法.

I'm trying to perform a group by action on an aliased column (example below) but can't determine the proper syntax.

SELECT       LastName + ', ' + FirstName AS 'FullName'
FROM         customers
GROUP BY     'FullName'

正确的语法是什么?

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编辑

进一步扩展问题(我没想到我收到了答案)该解决方案是否仍适用于 CASEed 别名列?

Extending the question further (I had not expected the answers I had received) would the solution still apply for a CASEed aliased column?

SELECT       
    CASE
        WHEN LastName IS NULL THEN FirstName
        WHEN LastName IS NOT NULL THEN LastName + ', ' + FirstName
    END AS 'FullName'
FROM         customers
GROUP BY     
    LastName, FirstName

答案是肯定的，它仍然适用.

And the answer is yes it does still apply.

推荐答案

您传递要分组的表达式而不是别名

You pass the expression you want to group by rather than the alias

SELECT       LastName + ', ' + FirstName AS 'FullName'
FROM         customers
GROUP BY      LastName + ', ' + FirstName

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