with t as
 ( select 1 rnum, '12345' code from dual union all
   select 1 rnum, '12345678' code from dual union all
   select 1 rnum, '123456444' code from dual union all
   select 2 rnum, '155' code from dual union all
   select 2 rnum, '12355' code from dual
 ),
n as (
      select  t.*,
              row_number() over(partition by rnum order by code) rn
        from  t
     )
select  *
  from  n
  pivot(
        max(code)
        for rn in (1,2,3,4,5)
       )
/

      RNUM 1         2         3         4         5
---------- --------- --------- --------- --------- ---------
         1 12345     123456444 12345678
         2 12355     155

SQL>