select dt, round(a/7,2), round(b/7,2)
from(
    select distinct date(order_time) dt,
    count(fare)over(order by date(order_time) range interval 6 day preceding) a, 
    count(if(fare is null, 1, null))over(order by date(order_time) range interval 6 day preceding) b 
    from tb_get_car_order) as tb1
where dt between '2021-10-01' and '2021-10-03'
order by dt