Hi friends. I have the following group of command in SQL:

SELECT table1.loanumber, 'CUOTA' =
CASE
WHEN sum(table1.amount) is null then 0
ELSE table1.amount
END
FROM table1
where table1.amount > 0
having CUOTA >0
GO


But, it send an error message : Invalid colun name 'CUOTA'
Really I have more command lines in this group but this is the central idea.
What can I do?...
Thanks in advance.

Carlos Burgos