select count(distinct device_id) did_cnt --device_id会做多道题目，会重复，使用distinct去重
,
(select count(id) question_id
from question_practice_detail
where date >= '2021-08-01' and date < '2021-09-01'
)
from question_practice_detail
where date >= '2021-08-01' and date < '2021-09-01'