#先找出有取消订单记录的司机
with a as(
select
distinct driver_id
from tb_get_car_record tr
join tb_get_car_order too
on tr.order_id = too.order_id
where date(too.order_time) between '2021-10-01' and '2021-10-31'
and fare is null)
#主查询——求每个司机
select IFNULL(driver_id, "总体") as driver_id,
round(avg(grade),1) as avg_grade

from tb_get_car_record tr
join tb_get_car_order too
on tr.order_id = too.order_id

where driver_id in (select * from a)
and grade is not null

group by driver_id
WITH ROLLUP


学到了一种求总体