Help on (sub)-select

Hi Folks,

I have two tables 

roster holds the duties to be performed and the number of people required per 
duty.
roster_staff holds the people allocated to perform that duty.

I'm trying to create a select that will tally the roster_staff and include it 
with the roster details.  I've managed to get it working for a specific day, 
but I can't seem to manage to get it working generically.

here's the select I've got that works, along with the output:

nymr=# select r.*, s.tally from roster r,
nymr-#     (select count(*) as tally from roster_staff where
nymr(#      rsdate = '2002-01-01' and rsgid = 11 and rsgsid = 2) as s
nymr-#   where rodate = '2002-01-01' and rogid = 11 and rogsid = 2;  rodate   | rogid | rogsid | rorequired |
rooptional| tally
 
------------+-------+--------+------------+------------+-------2002-01-01 |    11 |      2 |          0 |          1 |
  2
 
(1 row)

nymr=#

What I want to be able to do is select multiple rows and have the correct 
tally appear for that row.
-- 
Gary Stainburn
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