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