题解 | 计算25岁以上和以下的用户数量

select
    "25岁以下" as age_cut,
    count(id) as number
from user_profile
where age < 25 OR age is null

union 

select
    "25岁及以上" as age_cut,
    count(id) as number
from user_profile
where age >= 25