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

-- 按照商品类别分组，聚合销售额以及男女性的人数
SELECT 
    category_id,
    SUM(t2.order_amount) total_sales,
    SUM(IF(t1.customer_gender = '男',1,0)) male_customers,
    SUM(IF(t1.customer_gender = '女',1,0)) female_customers
FROM customer_info t1
LEFT JOIN order_details t2
ON t1.order_id = t2.order_id
WHERE t2.order_date BETWEEN '2024-01-01' AND '2024-06-30'
GROUP BY t2.category_id
ORDER BY t2.category_id