Adding Calculated Columns together to create a Total
You don't specify any specific RDBMS.

A method that should work in all/most would be to use a derived table.

SELECT Val1,
       Val2, 
       Val1 + Val2 AS Total
FROM 
(
Select Case
     ....
End as [Val1],
Select Case
     ....
End as [Val2]
From Table
) d /*&lt;-- arbitrary derived table alias*/


Probably you are on SQL Server (from the square brackets) in which case you could also use

SELECT Val1,
       Val2,
       Val1 + Val2 AS Total
FROM   TABLE
       CROSS APPLY (VALUES(Case ....End,Case ....End)) V( Val1, Val2) 


depending on the exact expression behind Val1 and Val2 (e.g. you can't use this and get correct results if they reference window functions).