Stefan
??
You would need to do as follows
column seq2 noprint;
select 1?? seq1 , 1 seq2 , column_a from table1
union
select 1?? seq1 , 2 seq2 , column_b from table1
union
select 2?? seq1 , 1 seq2 , column_c from table2
union
select 2?? seq1 , 2 seq2 , column_d from table2
order by seq , seq2
/

Hope this answers your question.

GovindanK

Ok, I didn't express well what I want to do. I want to put one table after the 
other. So the original table is
1 a b
2 c d
I want
1 a
1 b
2 c
2 d
in the view.
Thanks for answering.
Stefan