access查询不重复

我想查询显示整个表的数据。但是条件是其中一列不重复的显示出来。
例如：a b c
      1 2 3
      1 2 4
      1 3 5
结果我想显示
      a b c
      1 2 3
      1 3 5

也就是b列不重复

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up

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SQL code:
select
*
from
tb t
where
c=(select min(c) from tb where a=t.a and b=t.b)

---

SQL code:
----------------------------------------------------------------
-- Author :fredrickhu(我是小F，向高手学习)
-- Date :2009-12-22 15:08:10
-- Version:
-- Microsoft SQL Server 2005 - 9.00.4035.00 (Intel X86)
-- Nov 24 2008 13:01:59
-- Copyright (c) 1988-2005 Microsoft Corporation
-- Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)
--
----------------------------------------------------------------
--> 测试数据：[tb]
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([a] int,[b] int,[c] int)
insert [tb]
select 1,2,3 union all
select 1,2,4 union all
select 1,3,5
--------------开始查询--------------------------
select
*
from
tb t
where
c=(select min(c) from tb where a=t.a and b=t.b)
---------------