<?php
date_default_timezone_set('America/New_York');
$link = mysql_connect('localhost','user','pass');
if (!$link){
    die('could not connect to database');
}
mysql_select_db('database name');
if (!isset($_SESSION['on'])){
    session_start();
    $_SESSION['on'] = 1;
}
$usr['status'] = 0;
if (isset($_SESSION['status']) === true){
    $usr['status'] = $_SESSION['status'];
}
if (isset($_POST['login']) === true){
    $uname = mysql_real_escape_string($_POST['uname']);
    $upass = hash("sha512",$_POST['upass']);
    $login = mysql_query("SELECT * FROM `site_users` WHERE `login` = '".$uname."' AND `pass` = '".$upass."' AND `status` > '1'");
    if (mysql_num_rows($login)){
        $user = mysql_fetch_array($login);
        $_SESSION['name'] = $user['name'];
        $usr['name'] = $user['name'];
        $_SESSION['status'] = 2;
        $usr['status'] = 2;
    }
}
elseif (isset($_POST['logout']) === true){
    unset($_SESSION['status']);
}
if ($usr['status'] === 0){
    echo '<form method="post" action="#">
    <input class="text" type="text" value="Username" name="uname" size="8" />
    <input class="password" type="password" value="******" name="upass" size="8" />
    <input class="submit" type="submit" name="login" value="Login" />
    </form>';
}
else {
    echo '<form method="post" action="#">
    <input class="submit" type="submit" name="logout" value="Logout" />
    </form>';
}
?>