#题解 最大连续回答问题天数大于等于3天的用户及其对应等级#

#计算连续：当天-首日=排名-1  
with t1 as
(
select distinct author_id,answer_date,
min(answer_date) over(partition by author_id) mnd,
dense_rank() over(partition by author_id order by answer_date) as dr
from answer_tb
)
select author_id,author_level,max(dr)
from t1
inner join author_tb using(author_id)
where answer_date-mnd=dr-1 and dr>=3
group by author_id,author_level