--没用游标，你可以测试一下

declare @T table 
(Id int,UserId int,RemainingMoney numeric(2,1),ExpireDate datetime)
insert into @T
select 1,1,3.5,'2012-5-1' union all
select 2,2,3.5,'2012-5-1' union all
select 3,1,4.0,'2012-6-2' union all
select 4,1,5.0,'2012-6-1'

--给参数赋值
declare @userid int set @userid=1
declare @money int set @money=4
declare @j datetime
declare @k numeric(2,1)

;with maco as  
( select * from @T where UserId=@userid),
maco1 as
(  
select *,总金额=
(select sum(RemainingMoney) from maco where ExpireDate<=a.ExpireDate) from maco a
)  
select top 1 @j=ExpireDate,@k=总金额-@money from maco1 where 总金额>=@money  order by ExpireDate

update @T set RemainingMoney=@k where ExpireDate=@j and UserId=@userid 
update @T set RemainingMoney=0 where UserId=@userid and ExpireDate<@j  

select * from @T  
/*
Id          UserId      RemainingMoney                          ExpireDate
----------- ----------- --------------------------------------- -----------------------
1           1           0.0                                     2012-05-01 00:00:00.000
2           2           3.5                                     2012-05-01 00:00:00.000
3           1           4.0                                     2012-06-02 00:00:00.000
4           1           4.5                                     2012-06-01 00:00:00.000
*/