Received: from localhost (postgresql.org [64.49.215.8]) by postgresql.org (Postfix) with ESMTP id 126474762E3 for ; Fri, 24 Jan 2003 05:40:54 -0500 (EST) Received: from serwer.skawsoft.com.pl (serwer.skawsoft.com.pl [213.25.37.66]) by postgresql.org (Postfix) with ESMTP id 4C6E5476F55 for ; Fri, 24 Jan 2003 05:37:15 -0500 (EST) Received: from klaster.net (ph38.krakow.cvx.ppp.tpnet.pl [217.99.208.38]) by serwer.skawsoft.com.pl (Postfix) with ESMTP id 752872B887; Fri, 24 Jan 2003 10:54:56 +0100 (CET) Message-ID: <3E310F97.5050207@klaster.net> Date: Fri, 24 Jan 2003 11:04:07 +0100 From: Tomasz Myrta User-Agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; PL; rv:1.1) Gecko/20020826 X-Accept-Language: pl, en-us, en MIME-Version: 1.0 To: jack Cc: pgsql-sql@postgresql.org Subject: Re: quastions about primary key References: <00c301c2c374$1e698650$1400a8c0@jac> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by AMaViS new-20020517 X-Archive-Number: 200301/394 X-Sequence-Number: 11259 jack wrote: > Is that possible to have a two columns primary key on a table with null > value on second column? > > Jack Probably not, because (1,2,null,null) is unique for postresql. Watch discussion on mailing list about unique indexes (on which primary key is based) several days ago. Regards, Tomasz Myrta