Re: Summing & Grouping in a Hierarchical Structure

I would use the recursive CTE to gather the hierarchical portion of the data
you need and then join that CTE to another table or CTE with the other data
you need. I had a situation like this at my job were organization info was
in a hierarchal table and I needed to join it to two other tables. I created
a CTE with the combined data from the non-hierarchical tables and left
joined it to the recursive CTE.

If you're having trouble with this, I suggest looking into CTEs and the
different types of joins.

From: pgsql-sql-owner(at)postgresql(dot)org [mailto:pgsql-sql-owner(at)postgresql(dot)org]
On Behalf Of Don Parris
Sent: Thursday, February 21, 2013 4:38 AM
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] Summing & Grouping in a Hierarchical Structure

Hi Alexander,

I appreciate you taking time to reply to my post. I like the idea of the
WITH RECURSIVE query, but... The two examples in the link you offered are
not so helpful to me. For example, the initial WITH query shown uses a
single table, and I wander how that might apply in my case, where the
relevant information is actually found in two tables, one of them a
recursive table.

The second example, which applies the WITH RECURSIVE clause, is even less
so. I wonder if there is a good tutorial somewhere on this that shows some
other examples? That might help me catch on a little better. I'll search
for that today.

On Thu, Feb 14, 2013 at 11:30 PM, Alexander Gataric <gataric(at)usa(dot)net> wrote:

I would try a recursive
<http://www.postgresql.org/docs/8.4/static/queries-with.html> query to
determine the category structure and aggregate as you go. I had a similar
problem with a hierarchical structure for an organization structure. Another
thing you might try is to create a separate CTE for each category and then
aggregate the individual CTEs.

From: pgsql-sql-owner(at)postgresql(dot)org [mailto:pgsql-sql-owner(at)postgresql(dot)org]
On Behalf Of Don Parris
Sent: Thursday, February 14, 2013 7:58 PM
To: pgsql-sql(at)postgresql(dot)org
Subject: [SQL] Summing & Grouping in a Hierarchical Structure

Hi all,

I posted to this list some time ago about working with a hierarchical
category structure. I had great difficulty with my problem and gave up for
a time. I recently returned to it and resolved a big part of it. I have
one step left to go, but at least I have solved this part.

Here is the original thread (or one of them):
http://www.postgresql.org/message-id/CAJ-7yonw4_qDCp-ZNYwEkR2jdLKeL8nfGc+-TL
LSW=Rmo1VkbA(at)mail(dot)gmail(dot)com

Here is my recent blog post about how I managed to show my expenses summed
and grouped by a mid-level category:
http://dcparris.net/2013/02/13/hierarchical-categories-rdbms/

Specifically, I wanted to sum and group expenses according to categories,
not just at the bottom tier, but at higher tiers, so as to show more
summarized information. A CEO primarily wants to know the sum total for all
the business units, yet have the ability to drill down to more detailed
levels if something is unusually high or low. In my case, I could see the
details, but not the summary. Well now I can summarize by what I refer to
as the 2nd-level categories.

Anyway, I hope this helps someone, as I have come to appreciate - and I mean
really appreciate - the challenge of working with hierarchical structures in
a 2-dimensional RDBMS. If anyone sees something I should explain better or
in more depth, please let me know.

Regards,

Don

--
D.C. Parris, FMP, Linux+, ESL Certificate
Minister, Security/FM Coordinator, Free Software Advocate

http://dcparris.net/ <https://www.xing.com/profile/Don_Parris>

GPG Key ID: F5E179BE

--
D.C. Parris, FMP, Linux+, ESL Certificate
Minister, Security/FM Coordinator, Free Software Advocate

http://dcparris.net/ <https://www.xing.com/profile/Don_Parris>

GPG Key ID: F5E179BE