| From: | hubert depesz lubaczewski <depesz(at)depesz(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-bugs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: order by alias - doesn't work sometimes? |
| Date: | 2025-10-14 15:46:23 |
| Message-ID: | aO5wT-h2C5WACgaq@depesz.com |
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| Thread: | |
| Lists: | pgsql-bugs |
On Tue, Oct 14, 2025 at 11:10:31AM -0400, Tom Lane wrote:
> ORDER BY output-column-alias is a messy hangover from SQL92.
> In later SQL versions, identifiers in ORDER BY have the same
> interpretation as in WHERE and other clauses, namely they are
> columns sourced by the FROM clause. Supporting both interpretations
> makes for a lot of ambiguity, so we only allow the old interpretation
> in exactly the case required by SQL92, namely "ORDER BY identifier".
>
> This is documented ...
Well, now I understand this:
>> Each expression can be the name or ordinal number of an output column
>> (SELECT list item), or it can be an arbitrary expression formed from
>> input-column values.
better. Thanks.
Best regards,
depesz
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