chamilo / chamilo-lms

     * @param int $group_id iid

     * @return bool TRUE if given user is subscribed in given group

     */

    public static function is_subscribed($user_id, $group_id)

    {

        $course_id = api_get_course_int_id();

        if (empty($user_id) || empty($group_id) || empty($course_id)) {

            return false;

        }

        $table_group_user = Database :: get_course_table(TABLE_GROUP_USER);

        $group_id = intval($group_id);

        $user_id = intval($user_id);

        $sql = "SELECT 1 FROM $table_group_user

                WHERE

                    c_id = $course_id AND

                    group_id = $group_id AND

                    user_id = $user_id

                ";

        $result = Database::query($sql);

        return Database::num_rows($result) > 0;

    }

    /**

     * Can a user subscribe to a specified group in a course

     *

     * @return array

     */

    public static function getUserSession($userId, $sessionId)

    {

        $userId = intval($userId);

        $sessionId = intval($sessionId);

        if (empty($userId) || empty($sessionId)) {

            return false;

        }

        $table = Database::get_main_table(TABLE_MAIN_SESSION_USER);

        $sql = "SELECT * FROM $table

                WHERE session_id = $sessionId AND user_id = $userId";

        $result = Database::query($sql);

        $values = array();

        if (Database::num_rows($result)) {

            $values = Database::fetch_array($result, 'ASSOC');

        }

        return $values;

    }

    /**

     * Check if user is subscribed inside a session as student