X-Original-To: pgsql-sql-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 23010D1B19C for ; Mon, 28 Jun 2004 13:02:24 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 55372-02 for ; Mon, 28 Jun 2004 16:02:20 +0000 (GMT) Received: from web11.manitu.net (web11.manitu.net [217.11.48.111]) by svr1.postgresql.org (Postfix) with ESMTP id 26B71D1B181 for ; Mon, 28 Jun 2004 13:02:18 -0300 (ADT) Received: from [62.165.4.166] (dicaprio.akademie1.de [62.165.4.166]) (authenticated) by web11.manitu.net (8.10.2-SOL3/8.10.2) with ESMTP id i5SG1wa16281 for ; Mon, 28 Jun 2004 18:01:58 +0200 Subject: Empty array IS NULL? From: Markus Bertheau To: pgsql-sql@postgresql.org Content-Type: text/plain; charset=UTF-8 Message-Id: <1088438514.3239.97.camel@dicaprio.akademie1.de> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-7) Date: Mon, 28 Jun 2004 18:01:54 +0200 Content-Transfer-Encoding: quoted-printable X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.3 tagged_above=0.0 required=5.0 tests=UPPERCASE_25_50 X-Spam-Level: X-Archive-Number: 200406/270 X-Sequence-Number: 18215 Hi, is the empty array representable in PostgreSQL, and is it distinguishable from NULL? oocms=3D# SELECT ARRAY[1, 2]; array ------- {1,2} (1 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D1=8C) =20 oocms=3D# SELECT '{1, 2}'::INT[]; int4 ------- {1,2} (1 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D1=8C) =20 oocms=3D# SELECT ARRAY[]; ERROR: syntax error at or near "]" at character 14 oocms=3D# SELECT '{}'::INT[]; int4 ------ {} (1 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D1=8C) =20 oocms=3D# SELECT ARRAY(SELECT 1 UNION SELECT 2); ?column? ---------- {1,2} (1 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D1=8C) =20 oocms=3D# SELECT ARRAY(SELECT 1 WHERE FALSE); ?column? ---------- =20=20 (1 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D1=8C) =20 --=20 Markus Bertheau