I use a form for event registration off 1-day courses. The form writes the entries to a small MySQL database. Every registrant signs-up for the 1-day event and has to fill-out which workshops he/she wants tot participate in. The workshops can only have a maximum number of participants so I would like to have that the content of the form dynamic: if the in the php-form stated maximum of participants for the workshop is reached there is no more option to check it (but visitors can still see that it is in the event). See the attached demo application form for an example.