hierarchy system in mysql with php

[eluser]FutureKing[/eluser]
Hi,

I am building a custom cms for my website. I need to create category hierarchy system in my cms. That is admin can create delete edit categories according to his/her needs in any depth.
I need...
1) good tutorial about it
2) piece of already written code that I can use in my program.(if possible)
3) A good UI for managing categories.

Please help

I have a website in asp.net mssql. But I want to change it into php mysql. Currently I am using multiple tables for category-sub-category system. But it has its own limitation. For example I can not go to 3 level depth if I have only 2 tables. Therefore I want a good algorithm+program with which I can create such type of system in single table