Script na online

<?php
$time22 = (time()-60*15);
$online_uzivatele = MySQL_Query("SELECT count(user_id) as pocet_uzivatel FROM `uzivatele` WHERE pos_prihlaseni>".$time22." AND online = '1'") or die (mysql_error());
$result=mysql_fetch_array($online_uzivatele);

$pristup=time(); // aktualni cas  
$tolerance=time()+30; // 30sekund  
$kdo=$_SERVER["REMOTE_ADDR"];// ip adresa  
$result3 = mysql_query("SELECT * FROM online_guest WHERE kdo='".$kdo."'") or die (mysql_error());// zjisteni je-li ctenar jiz v databazi   
if (mysql_num_rows($result3)==0){  
     @mysql_query("insert into online_guest values(null,'".$kdo."','".$pristup."')") or die (mysql_error());//pridame ho  
 }else{   
     @mysql_query("UPDATE online_guest set cas=".$pristup." WHERE kdo='".$kdo."'") or die (mysql_error());//aktualizujeme cas  
     }  
 @mysql_query("delete from online_guest where cas<".$tolerance."") or die (mysql_error());//smazani jiz neplatnych udaju  
 $online_g = mysql_query("SELECT count(*) as pocet_guest FROM online_guest");//spocitani online lidi 
 $result2=mysql_fetch_array($online_g); 
 $online_uzivatel20 = $result['pocet_uzivatel'];
 $online_guest = $result2['pocet_guest'];
 $online_guest2 = $online_guest - $online_uzivatel20;//vypiseme pocet on-line ctenaru  
?>
<div class="top_box">
Online: <?php echo $online_uzivatel20; ?><br />
Gäste: <?php echo $online_guest2; ?><br />
</div>