题解 | 某乎问答高质量的回答中用户属于各级别的数量

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