phpindex

<?php
session_start();
include('database_1.php');

if (isset($_POST['submit']))
{

  $username = trim($_POST['username']);
  $password = trim($_POST['password']);
  $query = "SELECT * FROM users WHERE username='$username' AND password = md5('$password')";
  $resultnew = mysqli_query($mysqli,$query) or die(mysqli_error());
  $num_row = mysqli_num_rows($resultnew);
  $row=mysqli_fetch_array($resultnew);
  if($num_row ==1)
{
    $_SESSION['user_name']=$row['username'];
    header('Location:filespage.html');
}
else
{
echo "Invalid login";
}
}
?>