Select Code to Download

create table test_connect_by (
  parent     number,
  child      number,
  constraint uq_tcb unique (child)
);

insert into test_connect_by values ( 5, 2);
insert into test_connect_by values ( 5, 3);
...
insert into test_connect_by values (null,38);
insert into test_connect_by values (null,26);
insert into test_connect_by values (null,16);

select lpad(' ',2*(level-1)) || to_char(child) s 
  from test_connect_by 
  start with parent is null
  connect by prior child = parent;

38
  15
...
  1
  12
16