题解 | #某乎问答高质量的回答中用户属于各级别的数量#

select 
    case when author_level = 1 or author_level = 2 then '1-2级'
    when author_level = 3 or author_level = 4 then '3-4级'
    else '5-6级' end as level_cut,
    count(a.author_id) as num
from  
    author_tb as a
right join(
    select 
        author_id
    from 
        answer_tb
    where
        char_len > 100
) as b
on a.author_id = b.author_id
group by 1
order by num desc