题解 | 每个顾客购买的最新产品名称

with t as(
    SELECT o.customer_id,customer_name,product_name as latest_order,rank() OVER(PARTITION BY customer_id ORDER BY order_date DESC) as num FROM orders as o
    INNER JOIN customers as c ON o.customer_id=c.customer_id
    INNER JOIN products  as p ON o.product_id=p.product_id
)
SELECT customer_id,customer_name,latest_order FROM t WHERE num<=1