/**
* Count lesson users based on the specified constraints
* @param array $constraints The constraints for the query
* @return array An array of EfrontUser objects
* @since 3.6.3
* @access public
*/
public function countLessonUsers($constraints = array())
{
!empty($constraints) or $constraints = array('archive' => false, 'active' => true);
list($where, $limit, $orderby) = EfrontUser::convertUserConstraintsToSqlParameters($constraints);
$where[] = "u.login=ul.users_LOGIN and ul.lessons_ID='" . $this->lesson['id'] . "' and ul.archive=0";
$from = EfrontLesson::appendTableFiltersUserConstraints("users u JOIN users_to_lessons ul ON u.login=ul.users_LOGIN", $constraints);
$result = eF_countTableData($from, "distinct(u.login)", implode(" and ", $where));
return $result[0]['count'];
}