select period,count(*) get_car_num, round(sum(timestampdiff(second,event_time,end_time)/60)/count(*),1)avg_wait_time, round(sum(timestampdiff(second,order_time,ifnull(start_time,order_time))/60)/count(start_time),1)avg_dispatch_time from ( select distinct cr.order_id,cr.event_time,cr.end_time,co.ord...