题解 | 每个顾客购买的最新产品名称

SELECT 
    o.customer_id,
    c.customer_name,
    p.product_name AS latest_order
FROM (  -- 关键补充：主查询需要FROM关键字来关联子查询T1
    SELECT 
        customer_id,
        MAX(order_date) AS latest_order_date
    FROM orders
    GROUP BY customer_id
) T1
-- 关联订单表：匹配客户ID+最后下单日期，拿到该订单的完整信息
JOIN orders o ON o.customer_id = T1.customer_id AND o.order_date = T1.latest_order_date
-- 关联客户表获取姓名
JOIN customers c ON o.customer_id = c.customer_id
-- 关联商品表获取最后一次下单的商品名称
JOIN products p ON p.product_id = o.product_id
ORDER BY o.customer_id;