Re: Bug: aliasing in ORDER BY when UNIONing - Mailing list pgsql-hackers

Marko Kreen <marko@l-t.ee> writes:
> What works:
> # select o.id from op o union all SELECT -1 order by id;

This is valid SQL.

> # select o.id from op o union all SELECT -1 order by o.id;
> ERROR:  Relation 'o' does not exist

This is not valid SQL.  For one thing, the table alias "o" is not
visible outside the first component SELECT.

Yes, I know 7.0 took it... but its handling of ORDER BY on UNION
was pretty darn broken.
        regards, tom lane