X-Original-To: pgsql-sql@postgresql.org Received: from rtlocal.trade-india.com (mail-relay.trade-india.com [203.196.129.235]) by postgresql.org (Postfix) with SMTP id D98604766E6 for ; Fri, 7 Mar 2003 01:29:47 -0500 (EST) Received: (qmail 30637 invoked from network); 7 Mar 2003 06:29:07 -0000 Received: from unknown (HELO system67.trade-india-local.com) (192.168.0.67) by infocom-236-129-del.trade-india.com with SMTP; 7 Mar 2003 06:29:07 -0000 From: Rajesh Kumar Mallah Organization: Infocom Network Limited To: Stephan Szabo Subject: Re: sql question regarding count(*) Date: Fri, 7 Mar 2003 12:01:38 +0530 User-Agent: KMail/1.5 Cc: Tomasz Myrta , References: <20030306220603.P87448-100000@megazone23.bigpanda.com> In-Reply-To: <20030306220603.P87448-100000@megazone23.bigpanda.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200303071201.38192.mallah@trade-india.com> X-Archive-Number: 200303/176 X-Sequence-Number: 12216 On Friday 07 March 2003 11:41 am, Stephan Szabo wrote: > On Fri, 7 Mar 2003, Rajesh Kumar Mallah wrote: > > Tomasz did you notice the two queries are totally differet on different > > tables? > > A count() on a non-grouped table returns 1 row. > > A grouped table returns 1 row per group. If there are no groups, no rows > are returned. If the groups are filtered by a having clause, it might > also return no rows. True the second query does not return any row. even in first case no rows are returned. where is the difference? tradein_clients=# select userid from users where userid=-1; +--------+ | userid | +--------+ +--------+ (0 rows) Time: 846.86 ms tradein_clients=# Regds Mallah ---------------------------------------- Rajesh Kumar Mallah, Project Manager (Development) Infocom Network Limited, New Delhi phone: +91(11)6152172 (221) (L) ,9811255597 (M) Visit http://www.trade-india.com , India's Leading B2B eMarketplace.