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sub-selects 2+ messages / 2 participants [nested] [flat]
* sub-selects @ 2005-05-16 19:45 Mark Fenbers <Mark.Fenbers@noaa.gov> 0 siblings, 1 reply; 2+ messages in thread From: Mark Fenbers @ 2005-05-16 19:45 UTC (permalink / raw) To: pgsql-sql This is a multi-part message in MIME format. --------------090105060904060804060108 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#333399"> Is there a way to make a query more efficient by executing a sub-select only once?<br> <br> In a query such as:<br> <br> <tt>SELECT a, (select b from c where d = e limit 1), npoints( (select b from c where d = e limit 1) )<br> FROM f<br> WHERE isValid( (select b from c where d = e limit 1) );<br> </tt><br> I do the same sub-select 3 times in the query. I tried the following:<br> <br> <tt>SELECT a, (select b from c where d = e limit 1)<b> AS g</b>, npoints( <b>g</b> )<br> FROM f<br> WHERE isValid( <b>g</b> );<br> </tt><br> But this gave an error regarding "column 'g' does not exist". How can I avoid making the same sub-select 3 times? <br> <br> Mark<br> </body> </html> --------------090105060904060804060108 Content-Type: text/x-vcard; charset=utf-8; name="Mark.Fenbers.vcf" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="Mark.Fenbers.vcf" begin:vcard fn:Mark Fenbers n:Fenbers;Mark org:DoC/NOAA/NWS/OHRFC adr:;;1901 South SR 134;Wilmington;OH;45177-9708;USA email;internet:Mark.Fenbers@noaa.gov title:Sr. HAS Meteorologist tel;work:937-383-0430 x246 x-mozilla-html:TRUE url:http://weather.gov/ohrfc version:2.1 end:vcard --------------090105060904060804060108-- Attachments:^ permalink raw reply [nested|flat] 2+ messages in threadMark.Fenbers.vcf (text/x-vcard, 281B) download
begin:vcard fn:Mark Fenbers n:Fenbers;Mark org:DoC/NOAA/NWS/OHRFC adr:;;1901 South SR 134;Wilmington;OH;45177-9708;USA email;internet:Mark.Fenbers@noaa.gov title:Sr. HAS Meteorologist tel;work:937-383-0430 x246 x-mozilla-html:TRUE url:http://weather.gov/ohrfc version:2.1 end:vcard
* Re: sub-selects @ 2005-05-16 20:36 PFC <lists@boutiquenumerique.com> parent: Mark Fenbers <Mark.Fenbers@noaa.gov> 0 siblings, 0 replies; 2+ messages in thread From: PFC @ 2005-05-16 20:36 UTC (permalink / raw) To: Mark Fenbers <Mark.Fenbers@noaa.gov>; pgsql-sql SELECT foo.*, npoints( foo.g ) FROM (SELECT a, (select b from c where d = e limit 1) AS g FROM f WHERE isValid( g )) AS foo ? ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2005-05-16 20:36 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2005-05-16 19:45 sub-selects Mark Fenbers <Mark.Fenbers@noaa.gov> 2005-05-16 20:36 ` PFC <lists@boutiquenumerique.com>
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