• 限定条件：2021年8月，写法有很多种，比如用year/month函数的year(date)=2021 and month(date)=8，比如用date_format函数的date_format(date, "%Y-%m")="202108"
• 每天：按天分组group by date
• 题目数量：count(question_id)

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

1.然后可以用 substring（date,起点下标，截取个数）也可以获取   其中部分数据

2.然后匹配月份可以(比如想要八月份的内容的数据) ：date like '2021-08%'