题解 | 查询出不同类别商品中，销售金额排名前三且利润率超过 20%的商品信息

select product_id,product_name,category_id,sales_amount,profit_rate
from (
    select sales_and_profit.product_id,product_name,category_id,sales_amount,round((sales_amount-cost_amount)/sales_amount,2) as profit_rate,
           rank() over (partition by category_id order by sales_amount desc ) as rk
    from product_category join sales_and_profit
    on product_category.product_id=sales_and_profit.product_id
     ) as t
where rk<=3 and profit_rate >0.2