Mysqli bind_param

        $db = DB::getConnection();
       
        $db->prepare("INSERT INTO (type,kind) VALUES (?,?)");
        $db->bind_param('sss',$type_of_cable,$kind_of_cable);// недоступен метод bind_param
        $db->execute();// недоступен метод execute

final class DB {
 
    private static $host = '127.0.0.1';
    private static $user = 'root';
    private static $pass = 12345;
    private static $db_name = 'warehouse';
    private static $db;
 
    public static function getConnection() {
 
        if(self::$db === null) {
            $db = new mysqli(self::$host, self:: $user, self::$pass, self::$db_name);
            $db->set_charset('utf8');
            //$db->character_set_name();
            //$db->query("SET CHARACTER SET utf8");
            if(empty($db->errno)) {
                self::$db = $db;
            }
        }
        return self::$db;
    }
 
    private function __construct() {}
    private function __clone() {}
}

 $db->prepare("INSERT INTO item (type,kind) VALUES (?,?) ");
        $query = $db->bind_param('ss',$type_of_cable,$kind_of_cable);
        $db->execute();

$stmt = $mysqli->prepare("INSERT INTO CountryLanguage VALUES (?, ?, ?, ?)");
$stmt->bind_param('sssd', $code, $language, $official, $percent);
 
$code = 'DEU';
$language = 'Bavarian';
$official = "F";
$percent = 11.2;
 
$stmt->execute();

        $connect = $db->prepare("UPDATE item SET type=?, kind=?,fibers=?,kh=? WHERE id_item='$id' ");
        $connect->bind_param('ssii',$type_of_cable,$kind_of_cable,$fibers,$kh);
        $connect->execute();