Hierarchical Tree Menus in php??

[Ianto_Panto]

I am trying to create menus in php...What Im trying to create is a form to enter a person's birthday.

The user would enter the month, and then depending on their choice the day menu would contain 31, 30 or 28/29.....
I am reletively new to php, and would greatly appreciate any help offered.

The way I would think this works is by having the day menu empty, and when the user chooses a month the page reloads and enters the appropriate number of days into the day menu...
The problem I would have thought with this is, that when the page first loads it wouldn't know what the month variable is because it hasn't got a value yet....

What I need to know firstly is how I can implement a menu (month) that would send reload a page when someone chooses (and not having to click on a button)??

Thanks
ian

[_SuperString]

You cannot do this with just HTML, you will need to use some type of client script to get the form to reload the page without a button click.
If you are going to use something like JavaScript then why not just update the menu in real time (without the reload) ?