- 限定條件：2021年8月，寫法有很多種，比如用year/month函數的
year(date)=2021 and month(date)=8，比如用date_format函數的date_format(date, "%Y-%m")="202108" - 每天：按天分組
group by date - 題目數量：count(question_id)
selectday(date) as day,count(question_id) as question_cnt
from question_practice_detail
where month(date)=8 and year(date)=2021
group by date1.然后可以用 substring（date,起點下標，截取個數）也可以獲取? ?其中部分數據
2.然后匹配月份可以(比如想要八月份的內容的數據) ：date like '2021-08%'
)
