組由SQL

Question

計算字段

我寫這樣的

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 

我的產品要組一個查詢？ 如何做到這一點？

Answer 1

你需要做的是使用你的別名CASE列的子查詢。將您的查詢作爲子查詢，您可以group by您的別名列。

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

你需要在你的Group By的CASE爲好。不能使用別名在 GROUP BY

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