<?php

mysql_connect("MYSQL_SERVER_ADDRESS", "MYSQL_USERNAME", "MYSQL_PASS") or die(mysql_error());
mysql_select_db("MYSQL_DB") or die(mysql_error());

$user = strip_tags(mysql_escape_string($_POST['myusername']));
$pass = strip_tags(mysql_escape_string($_POST['mypassword']));

$getUser = mysql_query("SELECT * FROM usernames WHERE username = " . $user . "");

if (!$result) {
    die('Invalid Username');
}
else
{
    while($row = mysql_fetch_array($getUser))
    {
        if($pass == $row['password'])
        {
            $username = $row['username'];
            setcookie("username", $username, time()+7200);
        }
    }
}

?>