Re: faster output from php and postgres

On Tue, 2003-05-27 at 14:19, Richard Huxton wrote:
> On Tuesday 27 May 2003 5:34 pm, Chadwick Rolfs wrote:
> > So, I have the same problem, but I need all authors for each publication
> > to show up in it's own column. I tried the full join query from a
> > suggestion off pgsql-sql, but it only returns ONE author id TWICE instead
> > of ALL authors at once.
> >
> > I'll do some RTFMing of the joins.. and post any results I get
> >
> > BUT, right now, looping over each publication with php isn't taking that
> > long. I would like to know how to make this query, though!
> >
> > Please let me know how to get a result like:
> > ____________________________________________________
> >
> > |All Authors|Title|Source|Year|Type|Length|Keywords|
>
> Well, if you search the archives for terms "text", "concat", "aggregate" you
> should come up with one solution. This involves writing your own aggregate
> function, like SUM() but for text. Don't worry, it's not difficult. The only
> issue is that you won't be able to guarantee the order of authors in the
> field.

If order is required:

SELECT custom_aggregate(author) as authors
FROM (SELECT author FROM table ORDER BY author) AS tab;

The above should give you authors in alphabetical order if
custom_aggregate() was written to concatenate text.

--
Rod Taylor <rbt(at)rbt(dot)ca>

PGP Key: http://www.rbt.ca/rbtpub.asc