<?php
class Database
{
    private $user;
    private $pass;
    private $name;
    private $host;

    function __construct()
    {
        /* could also load a config file here to hold db data */
        $this->user = "username";
        $this->pass = "password";
        $this->name = "dbname";
        $this->host = "host:port";
    }

    protected function query($querystring,$returntype=1)
    {
        if($returntype == 1) /* return bool A.K.A. default return type */
        {
            if($handle = mysql_connect($this->host,$this->user,$this->pass))
            {
                if($tempo = mysql_query($querystring,$handle))
                {
                    mysql_close($handle);
                    $tempo = "";
                    return true;
                } else {
                    mysql_close($handle);
                    $tempo = "";
                    return false;
                }
            }
        } else if($returntype = 2) { /* return accociative array */
            if($handle = mysql_connect($this->host,$this->user,$this->pass)
            {
                if($tempo = mysql_query($querystring,$handle))
                {
                    if(mysql_num_rows($tempo) == 0)
                    {
                        mysql_close($handle);
                        return false;
                    } else {
                        // build custom accoc array for return
                    }
                }
            }
        } else {
            /*just here for language spec*/
        }
    }

    protected function encode($data)
    {
        if($handle = mysql_connect($this->host,$this->user,$this->pass)
        {
            $data = mysql_real_escape_string($data,$handle);
            mysql_close($handle);
            return $data;
        } else {
            return false;
        }
    }

    protected function decode($data)
    {
        return stripslashes($data);
    }

    function __destruct()
    {
      /* some garbage cleanup could go here if ever needed for db */
    }
}

/* you can put Database class in another file to make it mor organized and use require_once or whatever here */
class Login extends Database
{
    private function rnger()
    {
        for($i=0;$i<33;$i++)
        {
            $sid .= rng(0,9);
        }
        return $sid;
    }

    public function stat()
    {
        if(isset($_COOKIE["user"]))
        {
            // check id $_COOKIE["user"] against member db session
            $sid = $this->db_filter($_COOKIE["user"]);
            if($this->query("SELECT * WHERE sid = $sid",1)) return true;
        }
        return false;
    }

    public function logout()
    {
        /* destroy cookie and db entry */
        if(isset($_COOKIE["user"]))
        {
            setcookie("user","",time()-3600);
            $this->db_query("UPDATE `member` SET `session` = '' WHERE `session` = sidhere;");
        }
    }

    /* checks login+makes cookie and db entry for session id */
    public function login($user,$pass,$path,$domain,$duration)
    {
        $user = $this->filter($user);
        $pass = $this->filter($pass);
        if($this->query("SELECT * FROM `member` WHERE `username` = \'$user\' AND `password` = \'".md5($pass)."\';",1))
        {
            $sid = $this->rnger();
            if(!setcookie("user",$sid,$duration,$path,$domain)) return false;
            if(!$this->query("UPDATE `member` SET `session` = \'$sid\' WHERE `username` = \'".stripslashes($user)."\'",1))
            {
                setcookie("user","",time()-3600);
                return false;
            }
            return true;
        }
        return false;
    }

}
?>

<?php
/* Example check: */
auth = new Login();
if(auth->stat())
{
    /* user is logged in */
}
?>

<?php
auth = new Login();
if($_POST["username"] && $_POST["password"] && $_POST["submit"])
{
    /* expire in 1 hour */
    if(auth->login($_POST["username"],$_POST["password"],"/myname/www/","domain.com",time()+3600))
    {
        /* auth passed */
    } else {
        /* auth failed */
    }
}
?>