To prevent it, always add a randam value in querystring when calling a page.
This will let AJAX know that we need a page from server and not from Cache.

Originally Posted by badbart

Thanks to all of your guidance (this was my first time playing with AJAX), I've come up with a more configurable version of the cascading dropdown list code that my fellow Ajax-noobs might find helpful.

Here is what's in the attached zip:
AjaxCode.js - this is essentially the same as the other javascript files that have been posted here with a few minor tweaks.
data_settings.php - this is a file that's included in the php pages that query the database. It contains the hostname, username, password, and database name for the database that will house the tables, creates the database connection and selects the database.
index.php - this is a more dynamic main page that builds itself using two tables. The first table, ajax_data, contains all the data to be placed in the dropdowns. The second table, ajax_labels, contains the descriptions labels for each dropdown and more importantly, an id field that determines the value passed in the onchange event to load the dependent dropdown options.
tables.sql - this is the sql to build and fill the generic tables used by the code. You can add any number of dropdowns by adding records to ajax_labels and ajax_data with the proper corresponding id (in the label table) and parent & level (in the ajax_data table).
xml_data_provider.php - this is essentially the same file as was attached in the first post, with the required tweaks to make it work.