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 ut.author_level in (1,2) then '1-2级'
        when ut.author_level in (3,4) then '3-4级'
        else '5-6级' end as level_cut,
    count(issue_id) as num
from
    answer_tb at
left join 
    author_tb ut on at.author_id = ut.author_id
where 
    at.char_len >= 100
group by 
    1 
order by 
    2 desc