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
