chamilo / chamilo-lms

	 * @param string $current_username

	 * @return boolean True if username is available

	 */

	function validate($username, $current_username = null) {

		$user_table = Database::get_main_table(TABLE_MAIN_USER);

        $username = Database::escape_string($username);

        $current_username = Database::escape_string($current_username);

		$sql = "SELECT * FROM $user_table WHERE username = '$username'";

		if (!is_null($current_username)) {

			$sql .= " AND username != '$current_username'";

		}

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

		$number = Database::num_rows($res);

		return $number == 0;

	}

}

    * @param int  access url id

    * @return array   Database::store_result of the result

    **/

    public static function get_url_rel_course_data($access_url_id = null)

    {

        $where = '';

        $table_url_rel_course = Database :: get_main_table(TABLE_MAIN_ACCESS_URL_REL_COURSE);

        $tbl_course = Database :: get_main_table(TABLE_MAIN_COURSE);

        if (!empty($access_url_id)) {

            $where = " WHERE uc.access_url_id = ".intval($access_url_id);

        }

        $sql = "SELECT u.id, c_id, title, uc.access_url_id

                FROM $tbl_course u

                INNER JOIN $table_url_rel_course uc

                ON uc.c_id = u.id

                $where

                ORDER BY title, code";

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

        $courses = Database::store_result($result);

        return $courses;

    }

    /**

     * Gets the number of rows with a specific course_code in access_url_rel_course table

     * @return array   Database::store_result of the result

     *

     **/

    public static function get_url_rel_session_data($access_url_id = null)

    {

        $where ='';

        $table_url_rel_session = Database :: get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        $tbl_session = Database :: get_main_table(TABLE_MAIN_SESSION);

        if (!empty($access_url_id)) {

            $where = "WHERE $table_url_rel_session.access_url_id = ".intval($access_url_id);

        }

        $sql = "SELECT id, name, access_url_id

                FROM $tbl_session u

                INNER JOIN $table_url_rel_session

                ON $table_url_rel_session.session_id = id

                $where

                ORDER BY name, id";

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

        $sessions = Database::store_result($result);

        return $sessions;

    }

    /**

     *

     * @return array   Database::store_result of the result

     **/

    public static function get_url_rel_usergroup_data($access_url_id = null)

    {

        $where = '';

        $table_url_rel_usergroup = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USERGROUP);

        $table_user_group = Database::get_main_table(TABLE_USERGROUP);

        if (!empty($access_url_id)) {

            $where ="WHERE $table_url_rel_usergroup.access_url_id = ".intval($access_url_id);

        }

        $sql = "SELECT u.id, u.name, access_url_id

				FROM $table_user_group u

				INNER JOIN $table_url_rel_usergroup

				ON $table_url_rel_usergroup.usergroup_id = u.id

				$where

				ORDER BY name";

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

        $courses = Database::store_result($result);

        return $courses;

    }

    /**

     * Gets the inner join of access_url and the usergroup table

     * @param  int ID of the URL we want to filter on (optional)

     * @return int Number of sessions

     */

    public static function count_sessions($access_url_id = null)

    {

        $session_table = Database::get_main_table(TABLE_MAIN_SESSION);

        $access_url_rel_session_table = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        $sql = "SELECT count(id) FROM $session_table s";

        if (!empty($access_url_id) && $access_url_id == intval($access_url_id)) {

            $sql .= ", $access_url_rel_session_table u " .

                " WHERE s.id = u.session_id AND u.access_url_id = $access_url_id";

        }

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

        $row = Database::fetch_row($res);

        return $row[0];

    }

    /**

     * Protect a session to be edited.