How can I do this query:

Select
A,
B,
SUM(A + B) as C,
C * A as D ----->>>>> FB result on "C not Exists" error!
from
table
group by
A,
B

Of course, I can do this: "SUM(A + B) * A as D" to perform my query but,
I wish to learn if is possible the other one (C * A as D)

Thanks.
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Luigi Siciliano
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