Re: query: last N price for each product?

David Garamond wrote:
> Dear SQL masters,
>
> The query for "latest price for each product" goes like this (which I
> can grasp quite easily):
>
> SELECT * FROM price p1
> WHERE ctime=(SELECT MAX(ctime) FROM price p2 WHERE p1.product_id=p2.product_id)
>
> or:
>
> SELECT * FROM price p1
> WHERE NOT EXISTS (SELECT * FROM price p2 WHERE
> p1.product_id=p2.product_id AND p1.ctime < p2.ctime)
>
> but how do yo query for "latest 3 prices for each product"? The
> "price" table contains current price as well as price histories.

Is this what you are looking for...

SELECT * FROM price p1
WHERE ctime in (SELECT ctime FROM price p2 WHERE
p1.product_id=p2.product_id ORDER BY ctime DESC LIMIT 3)