How to find the top most member in a hierarchy of subcategories

[abhishek jain]

Hi,
I have a table structure like :
ID , NAME, PARENT_ID
1 , Top , 0
2 , Level 1 , 1
3 , Level 2 ,2
4 , Another Top , 0


and so on.
I wanted to know the topmost cat. if i have the lowest category id ie. 3 in
this case.
I wanted to get like 3->2->1
Pl. help me , cn i do this in one query, also i do not know how many
sublevels are there,
Thanks,
Abhishek jain