请教一个用sql语句实现数据集的自连接问题

[ivylxj]

请教论坛里各位高手一个问题：

某个数据集包含数据4列，itme1,value1,item2,value2
数据为：

I1,1,I2,1
I1,1,I3,1
I1,1,I5,1
I2,1,I3,1
I2,1,I4,1
I2,1,I5,1

请教如何写sql可以实现数据集的自连接，输出结果不重复，如以上数据集应输出：
I1,1,I2,1,I3,1
I1,1,I2,1,I4,1
I1,1,I2,1,I5,1
I2,1,I3,1,I4,1
I2,1,I3,1,I5,1
I2,1,I4,1,I5,1

[dawugui]

select distinct t1.* , t2.* , t3.* from
(
select itme1 itme, value1 value from tb
union 
select itme2 itme, value2 value from tb
) t1,
(
select itme1 itme, value1 value from tb
union 
select itme2 itme, value2 value from tb
) t2,
(
select itme1 itme, value1 value from tb
union 
select itme2 itme, value2 value from tb
) t3
where t1.item < t2.item and t2.item < t3.item

[dawugui]

create table tb (itme1 varchar(10),value1 int,item2 varchar(10),value2 int)
insert into tb values('I1',1,'I2',1)
insert into tb values('I1',1,'I3',1)
insert into tb values('I1',1,'I5',1)
insert into tb values('I2',1,'I3',1)
insert into tb values('I2',1,'I4',1)
insert into tb values('I2',1,'I5',1)
go

select distinct t1.* , t2.* , t3.* from
(
select itme1 item, value1 value from tb
union 
select item2 item, value2 value from tb
) t1,
(
select itme1 item, value1 value from tb
union 
select item2 item, value2 value from tb
) t2,
(
select itme1 item, value1 value from tb
union 
select item2 item, value2 value from tb
) t3
where t1.item < t2.item and t2.item < t3.item
order by t1.item , t2.item , t3.item

drop table tb

/*
item       value       item       value       item       value       
---------- ----------- ---------- ----------- ---------- ----------- 
I1         1           I2         1           I3         1
I1         1           I2         1           I4         1
I1         1           I2         1           I5         1
I1         1           I3         1           I4         1
I1         1           I3         1           I5         1
I1         1           I4         1           I5         1
I2         1           I3         1           I4         1
I2         1           I3         1           I5         1
I2         1           I4         1           I5         1
I3         1           I4         1           I5         1

（所影响的行数为 10 行）
*/

[ivylxj]

非常感谢~~~~