SELECT
day(date) AS day,
COUNT(question_id) AS question_cnt
FROM question_practice_detail
WHERE year(date)=2021 AND month(date) = 8 
GROUP BY date;

猛猛地学了一遍黑马的sql课程，现在基本对着笔记都能把题写出来

唯一忘了的是from、where和group by的顺序