CREATE TABLE `your_database`.`users` (
`id` INT PRIMARY KEY AUTO_INCREMENT ,
`user` VARCHAR( 25 ) NOT NULL ,
`pass` VARCHAR( 25 ) ,
`status` VARCHAR( 10 ),
) ENGINE = MYISAM ;

mysql_connect("server", "username", "password");
$q = mysql_query("SELECT * FROM your_database.users WHERE status='online'");
$n = mysql_num_rows($q); //COUNTS USERS ONLINE

echo 'Count users: '.$n;

session_start();
$session = $_SESSION['user'];
if($session)
{
echo '<b>'.$session.'</b>';
}
{
echo ' <table>
<tr><td align="right">Username:</td><td align="left"><input name="user"></td></tr>
<tr><td align="right">Password:</td><td align="left"><input name="pass" type="password"></td></tr>
</table>
<table width="250">
<tr><td align="left"></td><td align="right"><input name="submit" type="submit" value="Log In!"></td></tr>
</table><br>
}

session_start();
$session = $_SESSION['user'];
$user = $_POST['user'];
$pass = $_POST['pass'];

if(!$session)
{
if($user&&$pass){
mysql_connect("server", "username", "password");
$q = mysql_query("SELECT * FROM your_database.users WHERE user='$user' AND pass='$pass'");
$n = mysql_num_rows($q);

if($n){
$_SESSION['user'] = $user;
mysql_query("UPDATE your_database.users SET status='online' WHERE user='$user'"); //SETS STATUS AS ONLINE
session_write_close();
}
{
$q = mysql_query("SELECT * FROM your_database.users WHERE user='$user'");
$r = mysql_num_rows($q);
if($r){
echo 'Wrong Password <a href="index.php">Go back</a>';
}
{
echo 'Email not found <a href="index.php">Go back</a>';
}
}
}
{
echo 'Enter both fields <a href="index.php">Go back</a>';
}
}
{
header("Location: index.php");
}

session_start();
$user = $_SESSION['user'];
if($user)
{
mysql_connect('server', 'username', 'password');
mysql_query("UPDATE yourdatabase.users SET status='offline' WHERE user='$user'");

//DESTROYS SESSION
$unset = time()-60*60*24*365*10;
session_unset();
setcookie("user", $user, $unset, "/", ".yourdomain.com");
session_destroy();
ob_start();
ob_end_flush();
}
header("Location: index.php");