Null In Sql Query

hi
here is sql of query when any of sub query return zero result the result become null though other may have some results

litke

(select * from t1)-(select * from t)
in this case if either of table return zero rows the result will be null

plz help
thnx
faisal iqbal


sELECT bet.Party_id, (((select sum(amount*rate) from bet where team=1 and kl='l' and matchid = 18 and Party_id=1 )*1)-((select sum(amount*rate) from bet where team=1 and kl='k' and matchid = 18 and Party_id=1 )*1)) AS Expr1, (select sum(amount*rate) from bet where team=2 and matchid = 18 and bet.Party_id=1) AS Expr2, (select sum(amount*rate) from bet where team=3 and matchid = 18 and bet.Party_id=1) AS Expr3
FROM bet
GROUP BY bet.Party_id;