题解 | #分群并计算群体人数#

select
    case
        when age < 20 then '20以下'
        when age between 20 and 50  then '20-50'
        when age > 50 then '50以上'
        else '未填写'
    end age_group,
    count(customer_id) as user_count
from
    customers_info
group by
    age_group