select T1.id, T1.tbl1, T2.tbl2
from (
select U.id, U.tbl1, U.col
from tbl1
unpivot (tbl1 for col in (c1, c2, c3)) U
) T1
inner join
(
select U.id, U.tbl2, U.Col
from tbl2
unpivot (tbl2 for col in (c1, c2, c3)) U
) T2
on T1.id = T2.id and
T1.col = T2.col
order by T1.id