a good way to do this would be to create an inner join of the table to itself in the following syntax:
select a1.value, a2.value
from tablename a1
inner join tablename a2
on a1.commonfield=a2.commonfield
where a1.id < a2.id
for a more specific answer i will need to understand the table structure and some sample data in it
Hope this helps
Ohad