Статус пользователя на сайте (онлайн/ оффлайн)

<?php
$result = mysql_query("SELECT `id` FROM `users` WHERE `online` = '1'");
$row = mysql_fetch_array($result);
if(!isset($_SESSION['ID']))...
?>

$date = date("Y-m-d H:i");
$resultonline = mysql_query("UPDATE users SET timeout='$date' WHERE id='$id'",$db);

if ($myrow['timeout'] + '0000-00-00 00:30:00') > time()) {
print <<<HERE
офлайн
HERE;
}else{
print <<<HERE
онлайн
HERE;
}

$uslovie= SELECT timeout FROM users WHERE timeout < DATEADD(MINUTE, -30, GETDATE());
 
if ($uslovie == true) {
print <<<HERE
офлайн
HERE;
}else{
print <<<HERE
онлайн
HERE;
}

$uslovie=mysql_query(SELECT timeout FROM users WHERE timeout < DATEADD(MINUTE, -30, GETDATE());

$onstat = mysql_query(SELECT timeout FROM users WHERE id='$id', timeout < DATEADD(MINUTE, -30, GETDATE());
if ($onstat=='TRUE') {
print <<<HERE
офлайн
HERE;
}else{
print <<<HERE
онлайн
HERE;
}

$uslovie=mysql_query('SELECT timeout FROM users WHERE timeout < DATEADD(MINUTE, -30, GETDATE()) and id = ' . $id);

$date = date("Y-m-d H:i");
$resultonline = mysql_query("UPDATE users SET timeout='$date' WHERE id='$id'",$db);

$onstat = mysql_query("SELECT id FROM users WHERE id='$id' AND timeout < DATEADD(SECOND, -30, GETDATE()");
if ($onstat == '$id') {
print <<<HERE
онлайн
HERE;
}else{
print <<<HERE
Офлайн
HERE;
}

$onstat = mysql_query("SELECT id FROM users WHERE id='$id' AND timeout < DATEADD(MINUTE, -1, GETDATE())",$db);
$onlinestat = mysql_fetch_array($onstat);
if ($onlinestat['id'] == $id) {
print <<<HERE
онлайн
HERE;
}else{
print <<<HERE
Офлайн
HERE;
}

$onstat = mysql_query("SELECT id FROM users WHERE id='$id' AND timeout < DATEADD(MINUTE, -1, GETDATE())",$db);