[PHP] Problem: Access denied for user 'www-data'@'localhost'

<?
 error_reporting(E_ALL);
 session_start();
 include('./connect.php');
?>
...
<form action="login.php" method="POST">
 <input type="text" name="user" value="Username">
 <input type="password" name="pwd" value="Passwort">
 <input type="submit" name="login" value="Einloggen">
</form>

<?
 $host='localhost';
 $username='root';
 $password='meinpw';
 $db='CMS';
 $connection=mysql_connect($host,$username,$password) or die(mysql_error());
 $sql=mysql_select_db($db) or die(mysql_error());
?>

<?
$table='user';
if(isset($_POST['login'])) 
{
 $user=$_POST['user'];
 $pwd=$_POST['pwd'];
 if($sql=mysql_query("SELECT * FROM ".$table." WHERE username='".$user."' AND password='".$pwd."' LIMIT 1"))
 {
 echo('eingeloggt!');
 }
 else
 {
 echo('login fehlerhaft!');
 }
}
?>