Subtruction between 2 columns in a query

Question

Greeting Gurus,
i have the following query and what im trying to do is subtruct "TOTAL'' from ''By_PERIOD''. Is it possible to do it under these names or should i include both the select's into a new Sum?Thanks for any help in advnance
select a.cat,c.com,a.cat_desc,a.acnt_code, b.descr,
Sum(d.bas_amount) AS TOTAL,
Sum((select d.bas_amount from so_budgets d1 where d1.acnt_code = d.acnt_code
and Trim(d.period) BETWEEN '2008001' AND '2008006' AND ROWNUM=1)) BY_PERIOD,
Sum((SELECT kl.amount FROM a01_a_salfldg@oracle_to_sun kl WHERE Trim(kl.accnt_code)=Trim(a.acnt_code)
AND ROWNUM=1)) AS actual
from so_budgets_cat a,a01_acnt@oracle_to_sun b,so_budgets_com c,so_budgets d
where trim(a.acnt_code)=trim(b.acnt_code)
AND a.cat=c.cat
AND TRIM(d.acnt_code)=trim(a.acnt_code)
GROUP BY a.cat,a.acnt_code,c.com,a.cat_desc,b.descr
order by a.cat,a.acnt_code,c.com,a.cat_desc,b.descr
-------------------------------------------------------

Answer 1

create another column in your sql statement
SELECT a.cat,
        c.com,
        a.cat_desc,
        a.acnt_code,
        b.descr,
        SUM(d.bas_amount) AS total,
        SUM((SELECT d.bas_amount
             FROM   so_budgets d1
             WHERE  d1.acnt_code = d.acnt_code
             AND    TRIM(d.period) BETWEEN '2008001' AND '2008006'
             AND    rownum = 1)) by_period,
        SUM((SELECT kl.amount
             FROM   a01_a_salfldg@oracle_to_sun kl
             WHERE  TRIM(kl.accnt_code) = TRIM(a.acnt_code)
             AND    rownum = 1)) AS actual,
        ((SUM(d.bas_amount)) -
        (SUM((SELECT d.bas_amount
                FROM   so_budgets d1
                WHERE  d1.acnt_code = d.acnt_code
                AND    TRIM(d.period) BETWEEN '2008001' AND '2008006'
                AND    rownum = 1)))) sum_tot_per
FROM   so_budgets_cat         a,
        a01_acnt@oracle_to_sun b,
        so_budgets_com         c,
        so_budgets             d
WHERE  TRIM(a.acnt_code) = TRIM(b.acnt_code)
AND    a.cat = c.cat
AND    TRIM(d.acnt_code) = TRIM(a.acnt_code)
GROUP  BY a.cat,
            a.acnt_code,
            c.com,
            a.cat_desc,
            b.descr
ORDER  BY a.cat,
            a.acnt_code,
            c.com,
            a.cat_desc,
            b.descr