I am using following query which works fine for me except one problem

SELECT f.period as month, sum(p.revenue * ((100-q.rate)/100)) as revenue ,count(distinct q.label) as tot_stmt FROM files f, reports p, rates q,albums a where f.period in ('2010-06-01','2010-05-01','2010-04-01','2010-03-01') and f.period_closed = true and q.period = f.period and a.id = q.album_id and p.file_id = f.id and p.upc = a.upc and p.revenue is not null GROUP BY month ORDER BY month DESC

O/P =>
month            revenue     tot_stmt

2010-06-01     10.00         2
2010-05-01     340.47       2

I want result like following

month            revenue     tot_stmt

2010-06-01     10.00         2
2010-05-01     340.47       2
2010-04-01     0.00           0
2010-03-01     0.00           0

Regards,

Salil Gaikwad