先進行排序并且添加limit后可取最大值關聯的所有數據，如果不加limit則只有函數max里面的值是最大值，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 ;