$con=mysql_connect("localhost","root","alexi") or die('MySQL connect error!');

mysql_select_db("users") or die('MySQL select error!');

$username=$_POST['username'];
$pass=$_POST['password'];
$confirm_password=$_POST['confirm_passord'];

$password=md5($pass);

$queryuser=mysql_query("SELECT * FROM accounts WHERE username='$username'");
if (!$queryuser) {
  die('Username not found.');
}

$checkuser=mysql_num_rows($queryuser);
if($checkuser != 0) {
  echo "Sorry, ".$username." has already been taken.";
}
else {

  $insert_user=mysql_query("INSERT INTO accounts (username, password)
    VALUES ('$username', '$password')");

  if($insert_user)
    { echo "Registration Successfull"; }
  else
    { echo "error in registration".mysql_error(); }

}

mysql_close($con);