ORDER BY columns in a UNION
Hi all, I have a pair of statements connected by a UNION, where I need to sort the final result according to columns not appearing in any column list:
SELECT REF(d) FROM DOCUMENT_TABLE d
WHERE d.header$.parentKey = ?
UNION
SELECT REF(d) FROM DOCUMENT_TABLE d, CROSS_TABLE k
WHERE k.doc = d.key$ AND k.folder = ?
ORDER BY d.header$.name
this fails saying that d.header$.name is an invalid identifier (ORA-904), like being out of scope.
Both union branches succeed when run alone (select + order by).
How can I sort by colums without having them to be returned ?
In all examples I found columns are also retrieved and referenced by either alias or by position.
Thanks.