Changer d'include avec un bouton

<a href="page.php?var=1>Texte 1</a>
<a href="page.php?var=2>Texte 2</a>
<a href="page.php?var=3>Texte 3</a>

switch ($var)
{
   case 1:
   include ('texte1.html');
   break;

   case 2:
   include ('texte2.html');
   break;

   case 3:
   include ('texte3.html');
   break;

   default
   include ('page_par_defaut.html)
   break;
}