计算有关问题

计算问题
Sid             Money             Kid
1                   100                 1
1                   100                 2
1                   100                 3
2                   200                 1
2                   200                 2
3                   400                 5
没有主键，要求得到MONEY的和，但相同的Sid只计算一次MOney，即变量@a   =   100+200+400   =   700,如何过滤条件？

[解决办法]
select sum(money) from(select max( money)[money] from tab group by Sid)a
[解决办法]
select sum(Money) from (select Min(Money) as Money from 表 group by Sid)t
[解决办法]
select sum(hj) as 总合计
from (select min([Money]) as hj from 表名 group by Sid) t

[解决办法]

declare @t table(sid int,[money] int,kid int)

insert into @t select 1, 100, 1
insert into @t select 1, 100, 2
insert into @t select 1, 100, 3
insert into @t select 2, 200, 1
insert into @t select 2, 200, 2
insert into @t select 3, 400, 5

select sum([money]) from ( select sid,[money] from @t
group by sid,[money]) a

--
700