这个需求很普遍，解决方式有两种，例如
create table mx
(
PK int,
[name] varchar(8),
[service] varchar(8),
[time] datetime
)
go
insert into mx
select 1, 'A01', 'B01', '2009-10-1' union all
select 2, 'A01', 'B01', '2009-10-2' union all
select 3, 'A01', 'B02', '2009-10-4' union all
select 4, 'A01', 'B03', '2009-10-4'
go
需要的结果为
2, 'A01', 'B01', '2009-10-2'
3, 'A01', 'B02', '2009-10-4'
4, 'A01', 'B03', '2009-10-4'
第一种方式
select * from mx t where time =(select max( time ) from mx where name=t.name and service=t.service)
第二种方式
select * from mx m where not exists(select * from mx where mx.[service]=m.[service] and mx.[time]>m.[time])
以效率来说第一种效率要快些