跟上一道一样的解法

select
    device_id,gender,
    case
    when age < 20 then '20岁以下'
    when age between 20 and 24 then '20-24岁'
    when age >=25 then '25岁及以上'
    else '其他'
    end  age_cut
from 
    user_profile;