题解 | 某乎问答高质量的回答中用户属于各级别的数量

select level_cut,count(1) num
from answer_tb at
join(
select *,case when author_level between 1 and 2 then '1-2级' 
              when author_level between 3 and 4 then '3-4级'
              when author_level between 5 and 6 then '5-6级'end as level_cut
from author_tb) as t1
on at.author_id = t1.author_id
where char_len >= 100
group by level_cut
order by num desc

使用casewhen条件函数来区分等级