按SQL中的计算字段分组

Question

我写了这样的查询

CASE 
              WHEN [col1] = 's' THEN '1'
              WHEN [col1] = 't' THEN '2' 
              WHEN [col1] = 'u' THEN '3' 
              WHEN [col2] = 'v' THEN '4'
.......
END AS product,
SUM(col3)
FROM dbo.TableA

我想在产品上分组吗？ 怎么做？

Answer 1

您需要做的是为别名的CASE列使用子查询。 将查询作为子查询，您可以group by名列进行group by 。

select product
from
(
    select
    CASE  
        WHEN [col1] = 's' THEN '1' 
        WHEN [col1] = 't' THEN '2'  
        WHEN [col1] = 'u' THEN '3'  
        WHEN [col2] = 'v' THEN '4'
    END AS product, 
    SUM(col3) as Col3Sum
    FROM dbo.TableA 
) a
group by product

Answer 2

您还需要在Group By拥有CASE 。 您不能在GROUP BY使用别名

SELECT yourColumn, otherColumn
   , CASE 
        WHEN [col1] = 's' THEN '1'
        WHEN [col1] = 't' THEN '2' 
        WHEN [col1] = 'u' THEN '3' 
        WHEN [col2] = 'v' THEN '4'
     END AS Product
   , anotherColumn 
FROM yourTable
GROUP BY CASE 
            WHEN [col1] = 's' THEN '1'
            WHEN [col1] = 't' THEN '2' 
            WHEN [col1] = 'u' THEN '3' 
            WHEN [col2] = 'v' THEN '4'
         END