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 o
JOIN 
    customer_info 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;