Auto-updating nested categories selection boxes - LAMP

I need a script which will work on a LAMP server, created via PHP, which auto-displays a drill-down list of categories in select boxes from which the user can choose. Similar to Country, State, City, etc. I am working with a MySQL database table of categories. Each record includes four fields: a unique ID, a text-based name, a tiny int indicating whether the category has child categories, and a field indicating the category's parent. There are 4,030 rows in the database, which is unlikely to change often, but will be subject to change on an occasional basis (so it has to be in a database, not a flat file). I believe there are no more than 5 levels in the table, but that, too, may change, so the select boxes should continue to update infinitely (or to some large number). There are currently 29 top-level categories, and the majority of the rest of the records are in the second level. I think the answer to this is jQuery/Ajax, but neither of those are within my skill set. The final solution should contain extensive comments so that I may edit it in the future, if necessary. Please include in your bid a link to a working example of this type of thing that you have done before, as well as your time frame for completion. Thank you!