Select sum shown null value in left join SQL statement - sql-server-2000

Question

I have three tables and expecting the result as below but i do not know how to correct my sql statement.
select history.company,history.ghacct,rpt_revenue.revenue,rpt_revenue.other, isnull(guest.stay,0) as stay, isnull(guest.nights,0) as nights
from history
left join(select company,count(*) as stay,sum(nights) as nights from guest group by company) guest on guest.company=history.company
left join (select ghacct,sum(revenue) as revenue, sum(other) as other
from rpt_revenue group by ghacct) rpt_revenue on rpt_revenue.ghacct=history.ghacct
where history.type='c' group by history.company, history.ghacct,rpt_revenue.revenue, rpt_revenue.other,guest.stay,guest.nights order by history.company asc;
history
ghacct company type
33 JOINT LTD 10010205687 c
3B GLOBAL 10010350619 c
3E FASHION 10010244145 c
3P INT'L 10010112089 c
guest
company stay nights
33 JOINT LTD 01/01/2009 1
33 JOINT LTD 01/06/2009 1
3B GLOBAL 10/02/2019 2
3E FASHION 09/25/2008 6
3P INT'L 08/26/2009 3
3P INT'L 04/26/2010 9
rpt_revenue
ghacct revenue other
10010205687 20 10
10010205687 10 10
10010350619 30 2
10010244145 15 3
10010112089 16 8
10010112089 4 2
Result
company ghacct revenue other stay nights
33 JOINT LTD 10010205687 NULL NULL 2 2
3B GLOBAL 10010350619 NULL NULL 1 2
3E FASHION 10010244145 NULL NULL 1 6
3P INT'L 10010112089 NULL NULL 2 12
Expected result
company ghacct revenue other stay nights
33 JOINT LTD 10010205687 30 20 2 2
3B GLOBAL 10010350619 30 2 1 2
3E FASHION 10010244145 15 3 1 6
3P INT'L 10010112089 20 10 2 12

Answer 1

I think the main problem with your current query lies in the GROUP BY clause, which should really only be aggregating by company and account. In addition, you might want to use ISNULL for the revenue and other amount, as you are already doing so for stay and nights.
SELECT
h.company,
h.ghacct,
ISNULL(rr.revenue, 0) AS revenue,
ISNULL(rr.other, 0) AS other,
ISNULL(g.stay, 0) AS stay,
ISNULL(g.nights, 0) AS nights
FROM history h
LEFT JOIN
(
SELECT company, COUNT(*) AS stay, SUM(nights) AS nights
FROM guest
GROUP BY company
) g
ON g.company = h.company
LEFT JOIN
(
SELECT ghacct, SUM(revenue) AS revenue, SUM(other) AS other
FROM rpt_revenue
GROUP BY ghacct
) rr
ON rr.ghacct = h.ghacct
WHERE
h.type = 'c'
GROUP BY
h.company,
h.ghacct
ORDER BY
h.company;