From: | "Josh Berkus" <josh(at)agliodbs(dot)com> |
---|---|
To: | "Creager, Robert S" <CreagRS(at)LOUISVILLE(dot)STORTEK(dot)COM>, "'SQL - PGSQL'" <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Determine the time difference from records in a select |
Date: | 2001-06-13 21:22:43 |
Message-ID: | web-71614@davinci.ethosmedia.com |
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Lists: | pgsql-sql |
Robert,
> I have a firewall hit database which keeps the date of the hit and
> the
> offenders IP (among other items). I would like to be able to execute
> a
> select which would show each unique IP and the time difference from
> the
> latest hit to the first hit. I can do this in scripts, but was
> wondering if
> there is a pure SQL query/queries way to accomplish this.
You need to use a subselect in the FROM clause, which requires 7.1 or
greater.
SELECT agg_last.ip_addr, first_hit, last_hit, (last_hit- first_hit) AS
hit_interval
FROM
(SELECT ip_addr, max(hit_date) FROM hits GROUP BY ip_addr)
agg_last,
(SELECT ip_addr, min(hit_date) FROM hits GROUP BY ip_addr)
agg_first
WHERE agg_last.ip_addr = agg_first.ip_addr;
-Josh Berkus
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