Problém s mysql_fetch_row

<?php
$pk = $_GET['pk'];
if(isset($pk)){
 db_connect();
 $dotaz = "select obsah from stranky where nazev='$pk'";
 $res = mysql_query($dotaz);
 while($z = mysql_fetch_row($res)) {
 foreach($z as $s);
 }
 }

 else {
 db_connect();
 $dotaz = "select obsah form stranky where nazev='index'";
 $res = mysql_query($dotaz);
  while($z = mysql_fetch_row($res)) {

   foreach ($z as $s);
 }
 }

?>