From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Amos Hayes <ahayes(at)polkaroo(dot)net>, pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Find min and max values across two columns? |
Date: | 2006-03-27 13:56:29 |
Message-ID: | 20060327135629.GM80726@pervasive.com |
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Lists: | pgsql-sql |
On Fri, Mar 24, 2006 at 04:00:35PM -0500, Tom Lane wrote:
> Amos Hayes <ahayes(at)polkaroo(dot)net> writes:
> > I'm trying to build a query that among other things, returns the
> > minimum and maximum values contained in either of two columns.
>
> I think you might be looking for
>
> select greatest(max(columnA), max(columnB)) from tab;
> select least(min(columnA), min(columnB)) from tab;
>
> greatest/least are relatively new but you can roll your own in
> older PG releases.
And if you care about performance you might also try:
SELECT max(greatest(column_a, column_b) ...
SELECT min(least(column_a, column_b) ...
There may be a difference in performance between the two.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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