leetcode 1164 指定日期的產品價格

 

select p1.product_id, ifnull(p2.new_price,10) as price from 
(   
    select distinct product_id from Products
) p1
left join
(
    select product_id, new_price from Products
    where (product_id,change_date) in (
        select product_id, max(change_date) from Products 
        where change_date <= '2019-08-16'
        group by product_id
    )
) p2
on p1.product_id = p2.product_id

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