select a.name,b.name from A a ,A b where a.name < b.name

------解决方案--------------------
SQL code
if object_id('tb') is not  null
drop table tb

create table tb(name varchar(1))
insert into tb select 'a'
insert into tb select 'b'
insert into tb select 'c'
insert into tb select 'd'
select id=identity(int,1,1),* into # from( 
select * from (select 'a' as name1) a ,(select name from tb)a2
union 
select * from (select 'b' as name1) a ,(select name from tb)a2
union
select * from (select 'c' as name1) a ,(select name from tb)a2
union
select * from (select 'd' as name1) a ,(select name from tb)a2
)tp 
where name1<>name 

create table #2(name1 varchar(20),name varchar(20))

DECLARE cur CURSOR FOR
select name1,name from #
declare @name1 varchar(20),@name varchar(20)
OPEN cur
FETCH NEXT FROM cur into @name1,@name
insert into #2 select @name1,@name
FETCH NEXT FROM cur into @name1,@name
WHILE @@FETCH_STATUS = 0
   BEGIN
    if not exists(select 1 from #2 where name1+name=@name1+@name or name1+name=@name+@name1)
    insert into #2 select @name1,@name
      FETCH NEXT FROM cur into @name1,@name
   END
CLOSE cur
DEALLOCATE cur

select * from #2

------解决方案--------------------
create table tb(name varchar(1))
SQL code
insert into tb select 'a'
insert into tb select 'b'
insert into tb select 'c'
insert into tb select 'd'
select a.name as a,b.name as b from tb a,tb b 
where a.name<b.name order by a.name
drop table tb