title: php mysql insert date of birth
body: <p>I would like some help here.
  I'm having a registration form with fields like name, surname, dob (date of birth), email etc.
  When I'm trying to insert into my database everything works fine but for the dob.</p>
  
  <p>The dob I get it from 3 select-option menus like $_POST['year'], $_POST['month'], $_POST['day'], but i haven't find out yet how to put those 3 values in one (dob) in order to insert it in my database correct and not taking the value 0000-00-00.</p>
  
  <p>Any help will be appreciated.</p>