From: Jeff Boes <jboes@nexcerpt.com>
To: pgsql-sql@postgresql.org
Subject: Need query to separate rows by one field's value
Date: Tue, 18 Nov 2003 18:41:31 GMT
Message-ID: <021a9dcef9be53a70a73251b8fe9080a@news.teranews.com> (raw)
Here's a query challenge for you. Given:
table foo (
a integer primary key,
b integer check (b > 0))
with a limited number of rows (say, <= 10). Values in column "a" are
unique (obviously). Values in column "b" are not.
I want to find a set of values for "a" such that the sum of "b" values
is as close to one-half of the total sum of "b" over all rows. That is,
select 2.0*sum(b) from foo
where a in (...);
would be approximately the same as
select sum(b) from foo;
Likewise,
select 2.0*sum(b) from foo
where a NOT in (...);
would be approximately that value, too.
--
Jeff Boes vox 269.226.9550 ext 24
Database Engineer fax 269.349.9076
Nexcerpt, Inc. http://www.nexcerpt.com
...Nexcerpt... Extend your Expertise
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: jboes@nexcerpt.com
Subject: Re: Need query to separate rows by one field's value
In-Reply-To: <021a9dcef9be53a70a73251b8fe9080a@news.teranews.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox