How to get the root node for a child using connect by prior

Question

Hi,
I searched at many places to do this but not able to get the exact o/p sp posting my question here.
I have a table with parent_id and child_id columns. The levels of this parent_child can be many but my aim is to find the ultimate parent ( dont know the right term)
like if I have a child_node= xyz and its parent= pqr and its parents=lmn which might be ultimate parent which doesnt have any further parent.
So if i start with child_code= "xyz" then i should get the parent as "lmn" and not the immediate parent "pqr".
Please help.
Thanks,
Aashish

Answer 1

To find the Parent on emp table:
select empno,ename,level
from emp
where level=3
start with empno=7934
connect by  empno= prior mgrTo find the Child on emp table:
select empno,ename,level
from emp
where level=1
start with empno=7934
connect by prior empno=  mgrBut you need to know the level or position to specify the level of parent or child. But there are some other possible options available if we can know the requirement properly.
Edited by: Vasista on Jan 11, 2011 2:27 AM
Edited by: Vasista on Jan 11, 2011 2:30 AM