From: Stephan Szabo <sszabo@megazone23.bigpanda.com>
To: Matthew Nuzum <cobalt@bearfruit.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: show data from two tables together
Date: Wed, 15 Jan 2003 19:26:08 -0800 (PST)
Message-ID: <20030115191320.R98147-100000@megazone23.bigpanda.com> (raw)
In-Reply-To: <003d01c2bcfa$d2084b40$6700a8c0@mattspc>
On Wed, 15 Jan 2003, Matthew Nuzum wrote:
> Well, this is somewhat of a follow up to my previous post regarding self
> joins. Now what I'm hoping to do is "virtually" combine the results
> from two different record sets into one apparent record set.
Fortunately we have the set functions, specifically UNION ALL in this
case.
> Here is the skeleton of my application's data structure. There is a
> table called "folders" and a table called "files".
>
> They look like:
> | files | folders
> ============= ============
> x| fileid x| folderid
> | filename | foldername
> | folderid | parentid
> | dsply_order | dsply_order
>
> files.folderid is fk to folders.folderid, folders.parentid is field for
> self joining to folderid.
>
> As a side note, I'd probably need to add a field that would indicate 1
> if the file came from files otherwise count(folders.*) WHERE parentid =
> folderid so that I can see if the folder is empty.
>
> As another side note, this operation will be performed quite frequently
> and should be fast.
>
> As I think about it, it seems that the only logical way would be to do
> this at the application level, not inside postgres. Please correct me
> if I'm wrong.
Maybe something like (minus the number of files/empty part):
CREATE VIEW viewname AS
SELECT fileid, filename, folderid, dsply_order FROM files
UNION ALL
SELECT folderid, foldername, parentid, dsply_order FROM folders;
SELECT * from viewname where folderid=23 order by dsply_order;
Depending on whether you want a count of files or just an empty
or not, and whether you want info on whether a particular entry
is a file or folder, you'll probably need to add to the above.
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To: pgsql-sql@postgresql.org
Cc: sszabo@megazone23.bigpanda.com, cobalt@bearfruit.org
Subject: Re: show data from two tables together
In-Reply-To: <20030115191320.R98147-100000@megazone23.bigpanda.com>
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