Re: Change JOIN tutorial to focus more on explicit joins

From: Jürgen Purtz <juergen(at)purtz(dot)de>
To: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>
Cc: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Subject: Re: Change JOIN tutorial to focus more on explicit joins
Date: 2021-03-15 08:06:51
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On 15.03.21 03:47, Thomas Munro wrote:
> On Thu, Mar 11, 2021 at 2:06 AM David Steele <david(at)pgmasters(dot)net> wrote:
>> On 12/1/20 3:38 AM, Jürgen Purtz wrote:
>>> OK. Patch attached.
> + Queries which access multiple tables (including repeats) at once are called
> I'd write "Queries that" here (that's is a transatlantic difference in
> usage; I try to proofread these things in American mode for
> consistency with the rest of the language in this project, which I
> probably don't entirely succeed at but this one I've learned...).
> Maybe instead of "(including repeats)" it could say "(or multiple
> instances of the same table)"?
> + For example, to return all the weather records together with the
> location of the
> + associated city, the database compares the <structfield>city</structfield>
> column of each row of the <structname>weather</structname> table with the
> <structfield>name</structfield> column of all rows in the
> <structname>cities</structname>
> table, and select the pairs of rows where these values match.
> Here "select" should agree with "the database" and take an -s, no?
> + This syntax pre-dates the <literal>JOIN</literal> and <literal>ON</literal>
> + keywords. The tables are simply listed in the <literal>FROM</literal>,
> + comma-separated, and the comparison expression added to the
> + <literal>WHERE</literal> clause.
> Could we mention SQL92 somewhere? Like maybe "This syntax pre-dates
> the JOIN and ON keywords, which were introduced by SQL-92". (That's a
> "non-restrictive which", I think the clue is the comma?)

+1. All proposed changes integrated.
Kind regards, Jürgen Purtz

Attachment Content-Type Size
0005-query.patch text/x-patch 6.8 KB

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