Using alias in the same select - sql-server-2008

Question

Once I set an a column name like this SUM(someColumn) AS [ColumnName], how can I use it afterwards ?
Let's say I build a query like this :
SELECT SUM(foo.A + foo.B + foo.C + foo.D + foo.E) AS [TotalFoo],
SUM(bar.A + bar.B + bar.C + bar.D + bar.E) AS [TotalBar],
-- I need [TotalFooBar]
And in the same select I want the total of [TotalFoo] and [TotalBar]. Is it possible to refere to these columns ? I could do it the long way :
SELECT SUM(foo.A + foo.B + foo.C + foo.D + foo.E) AS [TotalFoo],
SUM(bar.A + bar.B + bar.C + bar.D + bar.E) AS [TotalBar],
SUM((foo.A + foo.B + foo.C + foo.D + foo.E) +
(bar.A + bar.B + bar.C + bar.D + bar.E)) AS [TotalFooBar]
It's ok in this exemple but I have way more columns and it's hard to follow. And then what if I have to use this column ([TotalFooBar])? I'll have to rewrite the whole SUM everytime ?
What I'm looking for is something like this :
SELECT SUM(foo.A + foo.B + foo.C + foo.D + foo.E) AS [TotalFoo],
SUM(bar.A + bar.B + bar.C + bar.D + bar.E) AS [TotalBar],
SUM([TotalFoo] + [TotalBar]) AS [TotalFooBar]
Is it even possible ?

Answer 1

No, you can't do this in the same SELECT statement, but you can use subquery:
SELECT
TotalFoo,
TotalBar,
TotalFoo + TotalBar AS TotalFooBar
FROM
(
SELECT SUM(foo.A + foo.B + foo.C + foo.D + foo.E) AS [TotalFoo],
SUM(bar.A + bar.B + bar.C + bar.D + bar.E) AS [TotalBar],
...
FROM ...
) AS sub
...
or a CTE:
WITH CTE
AS
(
SELECT SUM(foo.A + foo.B + foo.C + foo.D + foo.E) AS [TotalFoo],
SUM(bar.A + bar.B + bar.C + bar.D + bar.E) AS [TotalBar],
...
FROM ...
)
SELECT
TotalFoo,
TotalBar,
TotalFoo + TotalBar AS TotalFooBar
FROM CTE