create table sale(id varchar(10),name nvarchar(10))
insert into sale select '01','龙海'
insert into sale select '02','黄苑超'
insert into sale select '03','某某'
create table product(id varchar(10),productname nvarchar(10),amount int,price decimal(8,2),saledate datetime)
insert into product select '01','面包',10,2,'2011-6-8'
insert into product select '02','fsa',15,14,'2011-7-8'
insert into product select '01','faw',222,1.1,'2011-10-25'
insert into product select '03','fwas',110,1.4,'2011-6-30'
insert into product select '02','aedsa',44,1.5,'2011-10-27'
insert into product select '03','w3sa',88,1.5,'2011-10-31'
go
select a.name,sum(b.amount*b.price*0.05)提成
from sale a inner join product b on a.id=b.id
where b.saledate between '2011-10-01' and '2011-10-31'
group by a.name
/*
name       提成
---------- ---------------------------------------
黄苑超        3.3000
龙海         12.2100
某某         6.6000

(3 行受影响)

*/
go
drop table sale,product

------解决方案--------------------
SQL code

select t.* , RANK() over(order by val desc) 排名 from
(
  select m.id , m.name , isnull(sum(n.amount* n.price),0) val,n.saledate from sale m left join product n on m.id = n.id group by m.id , m.name
) t

where CONVERT(varchar(7),t.saledate ,120)='2011-10'

------解决方案--------------------
SQL code
select *
from 
(select ID,sum(amount*price*0.05) as bounds from product  where convert(varchar(7),SaleDate,120)='2011-10' group by ID)b
where Sale.ID=a.ID