From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Grzegorz Szpetkowski <gszpetkowski(at)gmail(dot)com> |
Cc: | pgsql-docs(at)postgresql(dot)org |
Subject: | Re: 7.2. Table Expressions suggestion about NATURAL JOIN |
Date: | 2011-06-13 17:00:34 |
Message-ID: | BANLkTiniY3RssH-WWjrzO2ULUzZd0OQnoQ@mail.gmail.com |
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Lists: | pgsql-docs |
On Tue, May 17, 2011 at 9:47 PM, Grzegorz Szpetkowski
<gszpetkowski(at)gmail(dot)com> wrote:
> 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.
Done, with different wording.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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