Вызов функции-члена fetchObject () при использовании sqlite

Я пытаюсь проверить с сервера, зарегистрирован ли пользователь или нет, вот мой код php:

<?php
error_reporting(E_ALL & ~E_NOTICE);
$dir = 'sqlite:/mumble-server.sqlite';
$dbh  = new PDO($dir) or die("cannot open the database");

if ($_POST['func'] == 1) {
$mobileUser = $_POST['phone'];
$res_list = "SELECT count(*) FROM appusers WHERE phone ='" . $mobileUser . "'";
$rock = $dbh->query($res_list);
while ($obj = $rock->fetchObject()) {
    $listing[] = $obj;
}
echo json_encode(array('reslogin' => $listing));
}

и вот мой код на стороне клиента (java):

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://192.168.2.26/SqliteTest/sqlite.php");
  try {
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("func", "1"));
    nameValuePairs.add(new BasicNameValuePair("phone", "09367701739"));
    Log.e("mainToPost", "mainToPost" + nameValuePairs.toString());
    UrlEncodedFormEntity form;
    form = new UrlEncodedFormEntity(nameValuePairs,"UTF-8");
    httppost.setEntity(form);
    HttpResponse response = httpclient.execute(httppost);
    InputStream inputStream = response.getEntity().getContent();
    MainActivity.InputStreamToStringExample str = new MainActivity.InputStreamToStringExample();
    responseLogin = str.getStringFromInputStream(inputStream);
    Log.e("response", "response -----" + responseLogin);
    jsonresponse = new JSONObject(responseLogin);
    responsemain = jsonresponse.toString();

  } catch (Exception e) {
    e.printStackTrace();
  }
  return null;

но я получаю ответ от сервера:

response -----<br /><b>Fatal error</b>:  Uncaught Error: Call to a member function fetchObject() on boolean in W:\xampp\htdocs\SqliteTest\sqlite.php:16Stack trace:#0 {main}  thrown in <b>W:\xampp\htdocs\SqliteTest\sqlite.php</b> on line <b>16</b><br />

а строка 16 - while ($obj = $rock->fetchObject()) { кто-нибудь знает, как я могу это исправить?

Я изменил свой PHP на

<?php
error_reporting(E_ALL & ~E_NOTICE);
$dir = 'sqlite:/mumble-server.sqlite';
$dbh  = new PDO($dir) or die("cannot open the database");
if ($_POST['func'] == 1) {
$mobileUser = $_POST['phone'];
$rock = $dbh->prepare("SELECT count(*) FROM appusers WHERE phone ='" . $mobileUser . "'");
$result = $rock->fetchAll(\PDO::FETCH_ASSOC);
echo json_encode(array('reslogin' => $result));
}

но теперь появляется эта ошибка:

response -----<br /><b>Fatal error</b>:  Uncaught Error: Call to a member function fetchAll() on boolean in W:\xampp\htdocs\SqliteTest\sqlite.php:8Stack trace:#0 {main}  thrown in <b>W:\xampp\htdocs\SqliteTest\sqlite.php</b> on line <b>8</b><br />