title: PHP session not renewing
body: <p>I have a logout script for my web app which is the following:</p>
  
  <pre><code>&lt;?php
  session_start();
  require_once("config.php");
  $logout_connect = mysql_connect($db_host, $db_user, $db_pass);
      if (!$logout_connect){
          die('Impossibile connettersi: ' . mysql_error());
      }else{
          mysql_select_db($db_name, $logout_connect);
          mysql_query("DELETE FROM valutazioni_recenti WHERE idutente = '".$_SESSION['userid']."' ");
          if(mysql_query("DELETE FROM sessions WHERE ssnid = '".$_SESSION['ssnid']."' AND userid = '".$_SESSION['userid']."'")){
              $_SESSION = array();
              $session_id = session_id();
              session_destroy();
              mysql_close($logout_connect);
              header("location: login.php?logout");
              exit();
          }
  
      }
  
  ?&gt;
  </code></pre>
  
  <p>It makes me logout the user correctly, but, as I save session data in a DB on login and delete them on logout, I can see that if I login with a session id like "096c02aefbb34jd175bfa89d4ec1235" when I logout and login again it gives me the same sessionid to that specific user.
  Is it normal? Is there a way to change it? Do I just have to mix it (or m5d it) with the login time??</p>