先進行排序並且新增limit後可取最大值關聯的所有資料，如果不加limit則只有函式max裡面的值是最大值，其他的均取的最小值的值

SELECT

id,business_id,

max( allot_number )

FROM

( SELECT id,allot_number,create_time,business_id FROM bus_allot_record ORDER BY business_id, create_time DESC LIMIT 100000000 ) a

WHERE

create_time >= "2019-10-21 10:20:00"

AND create_time <= "2019-10-21 13:30:00" and allot_number <> 1

GROUP BY

business_id ;