Data Display -- SQL Query?

Question

Hi
This might be simple but, I have no idea.. how to achieve this via a simple SQL Query..
Data in a column :
1
5
6
15
25
30
35
Should do a SELECT showing like this..
1 5
6 15
25 30
35 NULL
Thanks!

Answer 1

create table t1
(numcol     number);
insert into t1 values(1);
insert into t1 values(5);
insert into t1 values(6);
insert into t1 values(15);
insert into t1 values(25);
insert into t1 values(30);
insert into t1 values(35);
commit;
select odds.numcol, evens.numcol
from
   select numcol
         ,row_number() over (order by numcol) rn
   from
      select numcol
            ,row_number() over (order by numcol) rn
      from   t1
   where mod(rn,2) <> 0
)  odds
   select numcol
         ,row_number() over (order by numcol) rn
   from
      select numcol
            ,row_number() over (order by numcol) rn
      from   t1
   where mod(rn,2) = 0
)  evens
where odds.rn = evens.rn (+);
              NUMCOL               NUMCOL
                   1                    5
                   6                   15
                  25                   30
                  35