Call to a member function rowCount() on boolean

ini_set('display_errors','Off');
try {
    $db = new PDO('mysql:host=localhost;dbname=hope', 'root', '', array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
} catch (PDOException $e) {
    exit($e->getMessage());
}
$sql = $db->query("SELECT * FROM `site`");
if ($sql->rowCount() != 0) {
    $site = $sql->fetch();
}

PHP Fatal error: Uncaught Error: Call to a member function rowCount() on boolean in /var/www/html/index.php:30\nStack trace:\n#0 {main}\n thrown in /var/www/html/index.php on line 30

Ругается на строчку if ($sql->rowCount() != 0) {

в чем проблема?