| From: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
|---|---|
| To: | Wolfgang Walther <walther(at)technowledgy(dot)de>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Allow an alias to be attached directly to a JOIN ... USING |
| Date: | 2020-11-14 08:52:39 |
| Message-ID: | 91c3880a-de95-324d-1d75-3ed512b221b6@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 2020-08-03 19:44, Wolfgang Walther wrote:
> So given this:
>
> SELECT x.id FROM a LEFT JOIN b USING (id) AS x
>
> will this return NULL or a.id for rows that don't match in b? This
> should definitely be mentioned in the docs and I guess a test wouldn't
> be too bad as well?
This issue is independent of the presence of the alias "x", so I don't
think it has to do with this patch.
There is a fair amount of documentation on outer joins, so I expect that
this is discussed there.
--
Peter Eisentraut
2ndQuadrant, an EDB company
https://www.2ndquadrant.com/
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