Re: Sales report by month and item category

If I'm reading your question right, you want to use a group by statement
based on the category field of the table (or join table). You won't get a
flat readout like you show, but you would get a row based output that way:

Date | Category | Count
xyz | Bikes | 233
xyz | Cars | 324

If you don't have a category field, add one to the table somehow for every
product - that should make it work.

If you want Null (no data) fields to show up in your report, there are a
few ways to do that. Off the top of my head maybe using "coalesce" to
convert null to "0" would work (be careful as this can change averages
etc). Sometimes a left/right or outer join will work and won't have the
problem with summary data like coalesce.

Steve

On Thu, Aug 6, 2015 at 9:16 AM, Richard RK. Klingler <richard(at)klingler(dot)net>
wrote:

> Hello
>
> I'm currently using following query to report the monthly revenue of an
> online shop:
> (well…I just use pgsql on a KISS basis ;o)
>
> select date_trunc('month', orders.orderdate) as month,
> sum(orderitems.price * orderitems.orderitems2quantity) as revenue
> from orders, orderitems, product
> where orderitems.orderitems2orderid = orders.orderid
> and orderitems.orderitems2productid = product.productid
> group by date_trunc('month', orders.orderdate)
> order by month desc;
>
> gives:
>
> month | revenue
>
> ------------------------+----------
>
> 2015-08-01 00:00:00+02 | 1956.00
>
> 2015-07-01 00:00:00+02 | 13079.40
>
> 2015-06-01 00:00:00+02 | 10864.20
>
>
>
> But as the "product" items have categories assigned to them I would like
> to be able to also
> report based on categories, something like:
>
> month | bikes | cars | planes | submarines
>
> ------------------------+----------+----------+----------+------------
>
> 2015-08-01 00:00:00+02 | 233.00 | 4211.00 | 7833.50 | 723.35
>
>
>
> So far I'm using two queries called in a loop in my PHP code….but the
> problem there is that
> not all categories return a revenue for a specific month if nothing was
> sold in that month.
>
>
> Or is that not possible in a more or less simple query?
>
>
>
> thanks in advance
> richard
>
>
>