SELECT `id`,`class`, `class_section` FROM `teacher_timetable` WHERE `sem`=1 GROUP BY `teacher_timetable`.`class`, `teacher_timetable`.`class_section` ORDER BY `class` , `class_section`SELECT `id`,`class`, `class_section` FROM `teacher_timetable` WHERE `sem`=3 GROUP BY `teacher_timetable`.`class`, `teacher_timetable`.`class_section` ORDER BY `class` , `class_section`SELECT `id`,`class`, `class_section` FROM `teacher_timetable` WHERE `sem`=5 GROUP BY `teacher_timetable`.`class`, `teacher_timetable`.`class_section` ORDER BY `class` , `class_section`