题解 | 商品销售排名

select
        *
from (
    select
        pi.product_name,
        pi.price * a.cnt as total_price
    from
            product_info as pi
    left join (
        select
            product_id,
            count(pay_method) as cnt
        from 
                user_client_log
        where 
                pay_method != ''
        group by 
                product_id
    )a
    on 
            pi.product_id = a.product_id
    order by 
            total_price desc
)b
where 
        total_price is not null 
limit 2