From: Bruno Wolff III <bruno@wolff.to>
To: teknokrat <teknokrat@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: how do i get differences between rows
Date: Tue, 23 Dec 2003 21:31:56 -0600
Message-ID: <20031224033156.GB16470@wolff.to> (raw)
In-Reply-To: <brs64d$1u47$1@news.hub.org>
References: <brs64d$1u47$1@news.hub.org>
On Thu, Dec 18, 2003 at 12:21:35 +0000,
teknokrat <teknokrat@yahoo.com> wrote:
> I am after an sql query that can give the differnces between consecutive
> timestamp values in the resultset.
> anyone know how to do this?
I think you can do something like the following (untested) on most systems.
select a.stamp - (select max(stamp) from tablename
where tablename.stamp < a.stamp) from tablename;
For postgres this (also untested) might be faster if there is an index
on stamp.
select a.stamp - (select stamp from tablename where tablename.stamp < a.stamp
order by stamp desc limit 1) from tablename;
The above relies on timestamps being unique. The difference for the smallest
timestamp will be null.
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To: pgsql-sql@postgresql.org
Cc: bruno@wolff.to, teknokrat@yahoo.com
Subject: Re: how do i get differences between rows
In-Reply-To: <20031224033156.GB16470@wolff.to>
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