Thanks for responding. That was the tip I needed.
Regards,
Mark
On Sat, 13 Dec 2003 16:36:32 -0300
Martin Marques <martin@bugs.unl.edu.ar> wrote:
> El Sáb 13 Dic 2003 16:21, MT escribió:
> > Hi,
> >
> > I have an invoicing system using postgresql. Each time a customer makes a
> purchase, a new record is inserted into the "cart" table. The "cart" table,
> among other things, contains a customer_id field and a total for the amount
> purchased on the particular invoice. Now what I'd like to do is to calculate
> the total invoices for each customer in a given time interval, then list
> those customers in descending order from most paying to least paying. Could
> someone give me some pointers on how to construct an sql statement that would
> flush out this data.
>
>
> First, lets see how to get the info you want:
> SELECT sum(invoice) AS total, customer_id FROM cart
> GROUP BY cuotomer_id;
>
> Now you can order it by the total column, and maybe give it a LIMIT, in case
> you have to many costumers. :-)
>
> --
> select 'mmarques' || '@' || 'unl.edu.ar' AS email;
> -----------------------------------------------------------------
> Martín Marqués | mmarques@unl.edu.ar
> Programador, Administrador, DBA | Centro de Telemática
> Universidad Nacional
> del Litoral
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>
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> TIP 8: explain analyze is your friend
