public function upd($name, $surname, $group, $date_of_taking, $lib_card, $name_book, $id_lib) : array
    {
      $result = $this->mysqli->query("UPDATE info SET
        name = '".$this->mysqli->escape_string($name)."',
        surname = '".$this->mysqli->escape_string($surname)."',
        group = '".$this->mysqli->escape_string($group)."',
        date_of_taking = '".$this->mysqli->escape_string($date_of_taking)."',
        lib_card = '".$this->mysqli->escape_string($lib_card)."',
        name_book = '".$this->mysqli->escape_string($name_book)."'
        WHERE id = '".$this->mysqli->escape_string($id_lib)."';");
      var_dump($result);
      return array();
    }