users online

<?php
/* Configuratie van MySQL */ 
$mysql_host = "localhost"; 
$mysql_user = "username"; 
$mysql_pwd  = "passwd"; 
$mysql_db   = "database_name"; 

$mysql_port = 3306;  // dit is de standaard MySQL port 

$max_time   = 600;   // de timeout... Hoe lang is iemand non-actief totdat 
                     // hij/zij uit de database wordt verwijderd? (in sec.) 

/* Vanaf hier gaat de rest automatisch */ 

$db = @mysql_connect($mysql_host . ":" . $mysql_port,$mysql_user,$mysql_pwd) 
        or die ("Could not connect to MySQL server!"); 
mysql_select_db($mysql_db,$db) 
        or die ("Could not select database " . $mysql_db); 

$tables_result = mysql_list_tables($mysql_db); 
$TABLE_EXISTS = FALSE; 
for ($c = 0; $c < mysql_num_rows($tables_result); $c++) 
  if (mysql_tablename($tables_result,$c) == "users_online") { $TABLE_EXISTS = TRUE; } 

if (!$TABLE_EXISTS) 
  mysql_query("CREATE TABLE users_online (id INT NOT NULL auto_increment PRIMARY KEY, sess_id VARCHAR(100), time DATETIME)",$db); 

session_start(); 
$id = session_id(); 

$query = mysql_query("SELECT * FROM users_online WHERE sess_id = '$id'",$db); 
if (mysql_affected_rows() > 0) 
  mysql_query("UPDATE users_online SET time = now() WHERE sess_id = '$id'",$db); 
else 
  mysql_query("INSERT INTO users_online VALUES(0,'$id',now())",$db); 

$now = date("U") - $max_time; // $now = UNIX timestamp - $max_time 
$now = date("Y-m-d H:i:s",$now); 
mysql_query("DELETE FROM users_online WHERE time < '$now'",$db); 

$count_query = mysql_query("SELECT COUNT(*) as TOTAL FROM users_online",$db); 
$user_count  = mysql_result($count_query,0,"TOTAL"); 
?> 

<center>




<?php print $user_count ?> Online</center>