Sequentially sort articles by data from custom forms: Country > Town > Project

Hi,

I’d like to offer a selection-menu on my website that has the following behavior:

1. User selects country.
2. Then user selects town.
3. Then user selects project.
4. Then user sees articles that match his/her selections.

The problem is that values for country, town, and project are changing all the time. I cannot offer a list, I have to read out all available countries, towns and projects with each call.

The next problem is that it should be sequential: First the user has to select the country, THEN the towns (from this country) are shown, THEN the projects (in this town) are shown and finally the selected project is shown. Best it would be to have this whole thing done without reloading the page.

Any hints on how to do this? It’s a small web-project for my company. I have been chosen because I have a little knowledge of php and html, but this seems to be a much higher effort…

Thanks a lot!