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References: <BANLkTimtKpbzfd9mQM_R5=0VnTfc=gF0qQ@mail.gmail.com>
Date: Wed, 18 May 2011 03:52:35 +0200
Message-ID: <BANLkTine881x0Jb8NeO38baToKhZ3HHybA@mail.gmail.com>
Subject: Re: 7.2. Table Expressions suggestion about NATURAL JOIN
From: Grzegorz Szpetkowski <gszpetkowski@gmail.com>
To: pgsql-docs@postgresql.org
Content-Type: text/plain; charset=ISO-8859-1

2011/5/18 Grzegorz Szpetkowski <gszpetkowski@gmail.com>:
> http://www.postgresql.org/docs/9.0/static/queries-table-expressions.html
> http://www.postgresql.org/docs/9.0/static/sql-select.html
>
> Respectively:
>
> "Finally, NATURAL is a shorthand form of USING: it forms a USING list
> consisting of all column names that appear in both input tables. As
> with USING, these columns appear only once in the output table."
>
> and
>
> "NATURAL is shorthand for a USING list that mentions all columns in
> the two tables that have the same names."
>
> To make that comprehensive you can add something like: "Note that if
> there is no any "shared" column between tables, then NATURAL JOIN acts
> like ON TRUE (that is, tables are cross-joined)", because it's not
> obvious.
>
> thanks & regards,
> greg szpetkowski
>

My mistake "NATURAL JOIN", better is to just write "NATURAL".

thanks & regards,
greg szpetkowski