牛客网刷题学习SQL（八）

SQL28 计算用户8月每天的练题数量

问题分解：
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) day , count(question_id) question_id
from question_practice_detail qpd
where date_format(date,'%Y-%m')='2021-08'
group by day

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