Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 02FC89FB395 for ; Tue, 6 Mar 2007 11:32:55 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-new, port 10024) with ESMTP id 22711-02 for ; Tue, 6 Mar 2007 11:32:26 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 035359FB2E5 for ; Tue, 6 Mar 2007 11:32:37 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id l26FWZs7004737; Tue, 6 Mar 2007 10:32:35 -0500 (EST) To: Florian Weimer cc: pgsql-sql@postgresql.org Subject: Re: Selecting exactly one row for each column value In-reply-to: <82hcsy4do7.fsf@mid.bfk.de> References: <82hcsy4do7.fsf@mid.bfk.de> Comments: In-reply-to Florian Weimer message dated "Tue, 06 Mar 2007 16:03:36 +0100" Date: Tue, 06 Mar 2007 10:32:35 -0500 Message-ID: <4736.1173195155@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.06 tagged_above=0 required=5 tests=AWL, BAYES_50, SPF_HELO_PASS, SPF_PASS X-Spam-Level: X-Archive-Number: 200703/45 X-Sequence-Number: 27683 Florian Weimer writes: > For each value in the first column, I need one (and only one) matching > row from the table. A possible solution is: SELECT DISTINCT ON would do it, if you don't mind a non-portable solution. regards, tom lane