Neat query to create a tree?

Question

Hi all,
If i have these in a table:
Step Dependent_Step
100 0
140 100
200 100
200 140
250 100
Can anyone suggest a query that would create a nice tree showing dependencies? (not sure if it is possible)
In this example:
100 is not dependent on any steps
140 is dependent on 100
200 is dependent on 100 and 140
250 is dependent on 100

Answer 1

create table tree (
       father      integer ,
       son      integer
  4  );
Table created.
insert into tree values (100, NULL);
1 row created.
insert into tree values (100, 140);
1 row created.
insert into tree values (100, 200);
1 row created.
insert into tree values (140, 200);
1 row created.
SQL> insert into tree values (100, 250);
1 row created.
SQL>
SQL>
SQL> commit;
Commit complete.
SQL>
SQL> select son||' is dependent on '|| father from tree
  2  connect by prior father = son;
SON||'ISDEPENDENTON'||FATHER
140 is dependent on 100
200 is dependent on 100
200 is dependent on 140
140 is dependent on 100
250 is dependent on 100
is dependent on 100
6 rows selected.
SQL>