Thread: Calculating total amounts per clientid

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
theparticular 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
pointerson how to construct an sql statement that would flush out this data. 

Thanks for your help,

Mark

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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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
> -----------------------------------------------------------------
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 8: explain analyze is your friend