Re: a bit confused about distinct() function - Mailing list pgsql-sql

From Tena Sakai
Subject Re: a bit confused about distinct() function
Date
Msg-id FE44E0D7EAD2ED4BB2165071DB8E328C04E84A53@egcrc-ex01.egcrc.org
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In response to a bit confused about distinct() function  ("Tena Sakai" <tsakai@gallo.ucsf.edu>)
List pgsql-sql
<p><font size="2">Many thanks, Tom.<br /><br /> Regards,<br /><br /> Tena Sakai<br /> tsakai@gallo.ucsf.edu<br /><br
/><br/> -----Original Message-----<br /> From: Tom Lane [<a
href="mailto:tgl@sss.pgh.pa.us">mailto:tgl@sss.pgh.pa.us</a>]<br/> Sent: Sun 3/29/2009 10:49 AM<br /> To: Tena Sakai<br
/>Cc: pgsql-sql@postgresql.org<br /> Subject: Re: [SQL] a bit confused about distinct() function<br /><br /> "Tena
Sakai"<tsakai@gallo.ucsf.edu> writes:<br /> > I am a bit confused about distinct() function.<br /><br /> Your
confusionis in thinking that DISTINCT is a function.  It is not;<br /> it's just a keyword that modifies SELECT. 
Write<br/><br />         select distinct subjectid, markerid, allele1id, allele2id<br />         from
tsakai.mygenotype2<br/>         ...<br /><br /> The other syntax was being read as an implicit row constructor, like<br
/><br/>         select distinct row(subjectid, markerid, allele1id, allele2id)<br /><br /> which actually will work in
PG8.4, but does not in existing releases;<br /> and you likely wouldn't like the output format anyway, since it
would<br/> just be one composite column.<br /><br />                         regards, tom lane<br /><br /></font> 

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