题解 | #筛选限定昵称成就值活跃日期的用户#

# 找到昵称以『牛客』开头『号』结尾、成就值在1200~2500之间，且最近一次活跃（答题或作答试卷）在2021年9月的用户信息。


select 
    ui.uid,
    ui.nick_name,
    achievement
from user_info ui 
left join exam_record er on ui.uid = er.uid
left join practice_record pr on ui.uid = pr.uid
where nick_name like '牛客%号' and achievement between 1200 and 2500 
group by uid 
having date_format(max(er.submit_time),'%Y%m') = 202109 or date_format(max(pr.submit_time),'%Y%m') = 202109