как правильно объеденить таблицы?

[=master=]

вот, мучайтесь:

with t1 as
(
	select p1, p2,
		row_number() over (partition by t1.p2 order by t1.p1) rn
	from (	
		select 'запись 1' p1, 4 p2
		union
		select 'запись 2' p1, 4 p2
	) as t1
), t2 as
(
	select p1, p2,
		row_number() over (partition by t2.p2 order by t2.p1) rn
	from (	
		select 'запись 5' p1, 4 p2
	) as t2
) select t1.p1, tr.p1 from t1
	left join ( select t2.rn, t2.p1, t2.p2 from t2 
				full join t1 on t1.rn=t2.rn and t1.p1=t2.p1) tr on tr.rn=t1.rn