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 (
    select *
    from order_details
    where order_date>='2024-01-01' and order_date<='2024-06-30'
) a join customer_info b on a.order_id=b.order_id
group by category_id
order by category_id