From 6334ef86a732ae4330dc1c4c65adab8059f864f3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 8 Jan 2001 21:30:37 +0000
Subject: [PATCH] Document that we don't support ORDER BY with general
expressions on the output of UNION/INTERSECT/EXCEPT.
---
doc/src/sgml/ref/select.sgml | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 9dbc4958121..a34771571ec 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1,5 +1,5 @@
<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/select.sgml,v 1.35 2000/12/12 05:07:59 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/select.sgml,v 1.36 2001/01/08 21:30:37 tgl Exp $
Postgres documentation
-->
@@ -616,7 +616,12 @@ SELECT title, date_prod + 1 AS newlen FROM films ORDER BY newlen;
<programlisting>
SELECT name FROM distributors ORDER BY code;
</programlisting>
-
+ A limitation of this feature is that an ORDER BY clause applying to the
+ result of a UNION, INTERSECT, or EXCEPT query may only specify an output
+ column name or number, not an expression.
+ </para>
+
+ <para>
Note that if an ORDER BY item is a simple name that matches both
a result column name and an input column name, ORDER BY will interpret
it as the result column name. This is the opposite of the choice that
--
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