--- In firebird-support@yahoogroups.com, "Alberto Pesce"
<palberto@...> wrote:

>
> I need to make this query:
> the lower cost of product ordered for each oreder.
>
> this work well
>
> SELECT cod_art, MIN(cost)
> FROM orders
> GROUP BY cod_art
>
> but this return each row in orders
>
> SELECT order_ID, cod_art, MIN(cost)
> FROM orders
> GROUP BY order_ID, cod_art
>
> How can I add order_ID in the first query?

Imagine you had the following table

Orders
======

order_ID Cod_art Cost
-------- ------- ----
1 1 10
2 2 20
3 1 15
4 3 20
5 3 22

Your first query would return

Cod_art MinCost
------- --------
1 10
2 20
3 20

Now Cod_art 1 could be order_id 1 OR 3??
Cod_art 2 will be 2

How could you possibly tell which should go first? You cant.
Alexandre's second query is probably the one you want.

Adam