----------------------------
-- Author  :fredrickhu(小F，向高手学习)
-- Date    :2011-08-11 21:16:57
-- Verstion:
--      Microsoft SQL Server 2008 (RTM) - 10.0.1600.22 (Intel X86) 
--    Jul  9 2008 14:43:34 
--    Copyright (c) 1988-2008 Microsoft Corporation
--    Enterprise Evaluation Edition on Windows NT 5.1 <X86> (Build 2600: Service Pack 3)
--
----------------------------
--> 测试数据：[tb]
if object_id('[tb]') is not null drop table [tb]
go 
create table [tb]([col1] varchar(2),[col2] varchar(2),[col3] varchar(2))
insert [tb]
select 'a1','b1','c1' union all
select 'a1','b1','c1' union all
select 'a1','b2','c3' union all
select 'a2','b2','c3' union all
select 'a2','b2','c4' union all
select 'a2','b3','c5' union all
select 'a3','b4','c6'
--------------开始查询--------------------------
select
 * 
 from
  tb t 
 where
  not exists(select 1 from tb where (col1=t.col1 and col2>t.col2) or (col1=t.col1  and col3>t.col3))
----------------结果----------------------------
/* col1 col2 col3
---- ---- ----
a1   b2   c3
a2   b3   c5
a3   b4   c6

(3 行受影响)
*/