Re: complicated query (newbie..) - Mailing list pgsql-general

could provide greater assistance if you could post the database schema you're using

cheers (from across the pond)

Martin
GMT+5(this week)
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> Date: Thu, 9 Apr 2009 18:08:04 +0200
> From: mrkafk@gmail.com
> To: sam@samason.me.uk
> CC: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] complicated query (newbie..)
>
> Sam Mason wrote:
> > On Thu, Apr 09, 2009 at 04:47:32PM +0200, Marcin Krol wrote:
> >> I've got 3 tables: hosts (with host.id column) and reservation (with
> >> reservation.id column) in many-to-many relation, and reservation_hosts
> >> which is an association table (with reservation_id and host_id columns).
> >>
> >> So I've got this query which selects hosts and reservations under
> >> certain conditions:
> >
> > If you could describe what you want in words it would help more. I
> > think you want something like "I was a list of all hosts and their first
> > reservation that doesn't cover some specific date".
>
> It's somewhat complicated:
>
> What I'm trying to accomplish is producing list of hosts available
> within a specified timeframe.
>
> What I have is a table of hosts, table of reservations (containing id,
> start_date and end_date) and an association table reservation_hosts.
>
> I need a list of hosts, with accompanying reservations fulfilling
> certain (date-related) conditions.
>
> But there are two twists:
>
> - if host has reservation(s), but those do not fulfill the date
> conditions (the host is not available within a specified timeframe), the
> host obviously should NOT be listed
>
> - if host has no reservations at all, it obviously is available, so it
> should be listed
>
>
> > If that's correct; you've got a couple of choices, either turn the inner
> > join into an outer join and move it up to join onto the hosts, or get
> > rid of it completely and use the DISTINCT ON clause.
>
> I'll try doing smth with it..
>
> Regards,
> mk
>
>
>
>
>
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