select ifnull(driver_id,'总体') as driver_id,
round(avg(grade),1) as avg_grade
from 
tb_get_car_order a
left join tb_get_car_record b
on a.order_id = b.order_id
where (start_time is not null)
and
driver_id in (select driver_id
                        from tb_get_car_order b
                        where (start_time is null)
                        and (DATE_FORMAT(finish_time,'%Y-%m') = '2021-10'))
group by driver_id with rollup