题解 | 查询出每个品牌在不同月份的总销售额以及购买该品牌商品的用户的平均年龄

select
    category_id,
    sum(order_amount) as total_sales,
    sum(
        case
            when customer_gender = '男' then 1
            else 0
        end
    ) as male_customers,
    sum(
        case
            when customer_gender = '女' then 1
            else 0
        end
    ) as female_customers
from
    order_details as o
    inner join customer_info as c on o.order_id = c.order_id
where
    order_date between '2024-01-01' and '2024-06-30'
group by
    category_id
order by
    category_id;