selecting only two from a list of choices

[bins]

Can any one help?

I have put together a form that has a list of 13 choices [each with their own field in a mysql database] and the browser is only "allowed" to select two of the choices. They are presently set out as individual checkboxes.

What is the code for doing this?

I am very much a beginner with php, and have been dropped in the deep end - any hand holding would be very much appreciated.😕

[mrhappiness]

either you create two identical select boxes and check whether the user chose the same entry twice and destroy his comp

or

you display each possible choice as combobox and name all this boxes "qwerty[]"
now you have an array $_POST['qwerty'] and you can count how many entries it has