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Re: problem selecting multiple records (again!)

From: Manuel Sugawara <masm(at)fciencias(dot)unam(dot)mx>
To: "Giorgio Andreoletti - mentelocale" <giorgio(dot)andreoletti(at)mentelocale(dot)it>
Cc: <pgsql-novice(at)postgresql(dot)org>
Subject: Re: problem selecting multiple records (again!)
Date: 2001-06-05 22:01:14
Message-ID: m3g0de37th.fsf@dep1.fciencias.unam.mx (view raw or flat)
Thread:
Lists: pgsql-novice
something like

select * from events where ref in (select distinct ref from events limit 3);

will do what you want.

hth,
Manuel.

"Giorgio Andreoletti - mentelocale" <giorgio(dot)andreoletti(at)mentelocale(dot)it> writes:

> hi everyone,
> i already wrote to this list for the same problem.... i thought i had
> resolved it, but i was wrong !
> i'll explain my problem in a different (and simplier to understand) way:
> 
> suppose you have a table representing some events like this:
> 
> id  |  ref  |  date
> -----------------------
> 1  |  10  |  2001-05-10
> 2  |  10  |  2001-05-11
> 3  |  10  |  2001-05-12
> 4  |  20  |  2001-05-11
> 5  |  20  |  2001-05-13
> 6  |  30  |  2001-05-15
> 
> the "ref" field is used to match this table with an another table containing
> the description of the event in that date.
> So, in this example I have the same event (identified as '10') which is
> repeated 3 times, another event ('20') repeated twice, and an event with a
> single occurance ('30').
> now suppose that today is 2001-05-09 and i want to publish on my web-site
> the next 3 events:
> 
> doing a simple SELECT i will get :
> 
> 1  |  10  | 2001-05-10
> 2  |  10  |  2001-05-11
> 4  |  20  |  2001-05-11
> 
> but what i really wanted was :
> 
> 1  |  10  | 2001-05-10
> 4  |  20  |  2001-05-11
> 6  |  30  |  2001-05-15
> 
> i.e., i don't want to get more than one occurance of the same "ref".
> 
> plz help me since i'm getting crazy trying to solve this problem !!!
> keep in mind that i'll have a table with hundreds of event, so the faster
> way to get the result is the preferred :-)
> 
> the web publishing system is based on zope.
> 
> tnx for your help
> 
> ============================
> Giorgio Andreoletti - mentelocale S.r.l.
> responsabile hardware e networking
> responsabile sviluppo web
> www.mentelocale.it
> giorgio(dot)andreoletti(at)mentelocale(dot)it
> ============================
> 
> 
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Next:From: Nabil SayeghDate: 2001-06-05 23:48:15
Subject: Re: problem selecting multiple records (again!)
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Subject: selecting a column average into table

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