select channels.channel_desc, calendar_month_desc, 
       countries.country_iso_code,
       to_char(sum(amount_sold), '9,999,999,999') sales$
from sales, customers, times, channels, countries
where sales.time_id=times.time_id 
  and sales.cust_id=customers.cust_id 
  and customers.country_id = countries.country_id
  and sales.channel_id = channels.channel_id 
  and channels.channel_desc in ('direct sales', 'internet') 
  and times.calendar_month_desc in ('2000-09', '2000-10') 
  and countries.country_iso_code in ('gb', 'us')
group by 
  rollup(channels.channel_desc, calendar_month_desc, countries.country_iso_code)