If you were to log in, you'd be able to get more information on your fellow community member.
Interested readers should check out Joe Celko's nested set model for representing trees in SQL. No need to be locked into proprietary SQL dialects and probably a couple of orders of magnitude faster to query!
Here's some links...
+ http://www.intelligententerprise.com/001020/celko.jhtml
+ http://www.dbmsmag.com/9603d06.html
+ http://www.dbmsmag.com/9604d06.html
+ http://www.dbmsmag.com/9605d06.html
+ http://www.dbmsmag.com/9606d06.html
+ http://www.sqlteam.com/Forums/topic.asp?TOPIC_ID=14099
+ http://www.dbazine.com/oracle/or-articles/tropashko4
+ http://mrnaz.com/static/articles/trees_in_sql_tutorial/mptt_overview.php
Regards, Mattster