select
    day (date) as day,
    count(question_id) as question_cnt
from
    question_practice_detail
where
    2021 = year (date)
    and 8 = month (date) 
group by
    date

有其他的解法用的是模糊查询，眼前一亮，多一种思路，不过要考虑sql优化