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>=5 then '5-6级'
when author_level<=2 then '1-2级'
else '3-4级' end) level_cut,
count(answer_tb.author_id) num
from author_tb
join answer_tb
on answer_tb.author_id=author_tb.author_id
where char_len>=100
group by level_cut
order by num desc
用case when实现分级
