Tree/category view database using PHP

[fireblade]

i wan to develop a site using a database in a tree or category navigation sistem. say like a webdierctory which contans data in catogorised way or a e-book download site that is in categorisedd way of data..

How can i design my data base to do in that way? any idea, suggestion or soLid link frOm where i can learn that stretegy? any one help pls??/

[mlseim]

Like a PHP site map?
http://www.google.com/search?hl=en&q...=Google+Search