create table NP
(number tinyint
,pair tinyint)

insert into NP
select 1, 10 union all
select 1, 12 union all
select 2, 11 union all
select 2, 12 union all
select 3, 10 union all
select 3, 13 union all
select 4, 11 union all
select 4, 13 
--(8 row(s) affected)


/*
table:
1: 10 12
2: 11 12
3: 10 13
4: 11 13

results:
1 - 4
2 - 3

*/


-- GET ROWNUMBER FOR EACH PAIR
with cte_NP
as
	(select
	row_number() over (partition by number order by number asc, pair asc) as r_n
	,*
	from NP
	) 

-- JOIN ON ROWNUMBER TO GET EACH PAIR IN A ROW
-- USE OF 1 INNER JOIN BECAUSE WE ASSUME TO HAVE ONLY PAIRS OF TWO NUMBERS (!)
select 
	c2.r_n as r_n1
	,c2.number as number1
	,c2.pair as pair1
	,c1.r_n as r_n2
	,c1.number as number2
	,c1.pair as pair2
into #temp
from cte_NP as c1
	join cte_NP as c2
	on c1.r_n = c2.r_n+1 and c1.number = c2.number
--(4 row(s) affected)


create table NP_PAIR_RESULTS (pair1 smallint,pair2 smallint)


declare @max_numbers smallint = 0
select @max_numbers = max(number1) from #temp
declare @stevc smallint = 1

while 
	@stevc <= @max_numbers
		begin
			declare @pair1 smallint
			declare @pair2 smallint
-- GET NUMBERS BY PAIRS INTO VARIABLES 
			select @pair1 = pair1 from #temp where number1 =@stevc	
			select @pair2 = pair2 from #temp where number1 =@stevc	

-- GET ALL COMBINATIONS OF PAIRS IN TABLE OF RESULTS
			insert into NP_PAIR_RESULTS								
			select @stevc as pair1
					,number1 as pair2
						from #temp 
							where 
								pair1 <>  @pair1
							and pair2 <>  @pair2
		
			set @stevc = @stevc + 1
		end

drop table #temp


-- ALL COMBINATIONS
select * from NP_PAIR_RESULTS

drop table NP
drop table NP_PAIR_RESULTS