On Fri, Mar 24, 2006 at 02:29:10PM -0800, Stephan Szabo wrote: > > On Fri, 24 Mar 2006, Julie Robinson wrote: > > > This works, but is there a better solution? > > > > select * > > from quality_control_reset T > > where date = ( > > select max(date) > > from quality_control_reset > > where qualitycontrolrange = T.qualitycontrolrange); > > If you can use PostgreSQL extensions (and don't care that you might not > get two rows if two ids had the same date equaling the max date for a > given range), maybe something like: > > select distinct on (qualitycontrolrange) id, date, qualitycontrolrange > from quality_control_reset order by qualitycontrolrange,date desc; > > > Otherwise, you might see how the above compares in plan to something like > (not really tested): > > select T.* from quality_control_reset T inner join > (select qualitycontrolrange, max(date) as date from quality_control_reset > group by qualitycontrolrange) T2 > on (T.qualitycontrolrange = T2.qualitycontrolrange and T.date=T2.date);
BTW, I believe the new row operator fixes in 8.2 make it possible to use them to do this kind of thing as well... -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
