题解 | #计算25岁以上和以下的用户数量#

select
    (
        case
            when b.rangeAge = 1 then '25岁以下' else '25岁及以上'
        end
    ) as age_cut,
    count(1) as number
from
    (
        select
            (
                case
                    when a.age is null then 1
                    when a.age < 25 then 1
                    else 0
                end
            ) as rangeAge
        from
            user_profile a
    ) b
group by
    b.rangeAge

这样写虽然很蠢，但能联系练习练习case when