Re: Basic SQL question and kudos

Thanks for the start. I'll start on it.

Dennis Gearon

Signature Warning
----------------
EARTH has a Right To Life,
otherwise we all die.

Read 'Hot, Flat, and Crowded'
Laugh at http://www.yert.com/film.php

--- On Tue, 10/5/10, Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> wrote:

> From: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>
> Subject: Re: [GENERAL] Basic SQL question and kudos
> To: "Dennis Gearon" <gearond(at)sbcglobal(dot)net>
> Cc: pgsql-general(at)postgresql(dot)org
> Date: Tuesday, October 5, 2010, 9:13 PM
> On 10/06/2010 12:31 AM, Dennis Gearon
> wrote:
> > I need to get a join across about 8 tables to only
> return rows for the MAX date in one of the tables for all
> otherwise identical return results. I am trying to get the
> most recent edit of normalized records that are composed of
> elements from all the tables. There could be 1 to 100+
> successive edits to the normalized/multi table record. The
> will be approximately 65,000 total records for now,
> 100,000,000s later.
> >
> > If I make one of the values in the select statement be
> MAX(the date), does that automatically do grouping on 'the
> date' or will I only get ONE row total returned?
>
>
> If I understand what you're proposing correctly, I don't
> think it'll work.
>
> What you need to do is use a subquery to obtain the max of
> the field of interest, and filter in your WHERE clause so
> you only return results when the selected value is the
> maximum for that field.
>
> It's hard to be more specific with a fairly general
> question like this, but if I'm understanding you right this
> is how I'd start.
>
> --
> Craig Ringer
>