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Subject: Re: Your question about date
From: =?ISO-8859-1?Q?B=E9atrice?= Yueksel <beatrice.yueksel@it-raum.ch>
To: Christoph Haller <ch@rodos.fzk.de>
Cc: Octavio Alvarez <alvarezp@tecbc.mx>, pgsql-sql@postgresql.org
In-Reply-To: <423E99E2.7D428966@rodos.fzk.de>
References: <opsnuhhzgwg6g4in@octavio.tecbc.mx>
	<423E99E2.7D428966@rodos.fzk.de>
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Date: Mon, 21 Mar 2005 11:59:18 +0100
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Dear Christoph,
perhaps you could try something like this example.
Regards,
Béatrice

The table:
----------
# select * from test;
    date
------------
 2005-02-02
 2005-03-05
 2005-04-07
 2005-05-02
(4 rows)


The query
----------

SELECT
 (( select test1.date
           from test test1
           where test1.date > test.date limit 1)
   - test.date ) AS result from test;

t1.date >
RESULT:
-------
 result
--------
     31
     33
     25



Am Montag, den 21.03.2005, 10:54 +0100 schrieb Christoph Haller:
> Octavio Alvarez wrote:
> > 
> > Sorry, I tried to make my subject as good as possible.
> 
> Ahem, what subject? 
> > 
> > I have a table where I store the dates in which I take out of my inventory
> > (like "installation dates")
> > 
> > table
> > ---------------
> > row_id   SERIAL
> > date     DATE
> > fk_item  INTEGER
> > 
> > and that's pretty much it.
> > 
> > I want to have a query returning how long have been certain items lasting.
> > 
> > Say I have:
> > 
> > SELCT date FROM table WHERE fk_item = "INKJET_INK-BW"
> > 
> > date
> > -------------
> > 2005-02-02
> > 2005-03-05
> > 2005-04-07
> > 2005-05-02
> > 
> > I need something to calculate the intervals between those dates, like this:
> > 
> > intervals (in days)
> > --------------------
> >   31
> >   34
> >   25
> > 
> > So I can get the stddev and stuff from the "duration" of the items.
> > 
> > I've been having a hard time with it. I'm trying NOT to program new
> > functions.
> 
> I cannot see how this could be achieved without the use of a function. 
> But if there is a way after all, I would be interested in learning it. 
> > 
> > Any help will be appreciated.
> > 
> > --Octavio
> > --
> 
> Regards, Christoph
> 
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