select 
date_format(date,'%d') as day,
count(question_id) as question_cnt
from question_practice_detail
where date between "2021-08-01" and "2021-08-31"
group by day

#其他解法
# select day(date) as day,
# count(question_id) as question_cnt
# from question_practice_detail
# where date like "%2021-08%"
# group by date

记录其他解法