if (isset($_GET[posted]))
{
    if(!empty($_GET['login'] && !empty($_GET['pass'])))
    {
        $login = $_GET['login'];
        $pass = $_GET['pass'];
        $link = mysql_connect("localhost", "skident", "pJUMZxXk") or die ("Невозможно        подключиться к серверу");
        mysql_select_db("skident", $link);
        $sql = "SELECT * FROM `user` WHERE `login` = '".$login."' and `pass` = '".$pass."'";
        $result=mysql_query($sql); 
        $row=mysql_fetch_array($result);  //вносим данные в БД
        
        if($row)
       {
           session_start();
           $_SESSION['id'] = $row['id'];
           $_SESSION['login'] = $row['login'];
           $_SESSION['pass'] = $row['pass'];
       }
    }
}
else
{
    echo "<form action=index.php method = GET>
    <input type = hidden name = posted>
    Введите login:<br>
    <input type = text name = login><br><br>
    Введите пароль:<br>
    <input type = password name = pass><br><br>
    <input type = submit value = Login>
		";
}