From: Tim Landscheidt <tim@tim-landscheidt.de>
To: pgsql-sql@postgresql.org
Subject: Re: UNION or LEFT JOIN?
Date: Tue, 16 Feb 2010 21:38:19 +0000
Message-ID: <m3635wuaic.fsf@passepartout.tim-landscheidt.de> (raw)
References: <20100216140814.GA22577@apartia.fr>
Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org> wrote:
> Here is the basic schema:
> -------------------------->id_ship>-----------------------
> | |
> [SHIP]->id_ship->[CABIN]->id_cabin->[PRICE]<-id_cruise<-[CRUISE]
> It's a database of cruise prices.
> Each 'price' object has a reference to 'cabin' and 'cruise'
> 'cabin' belongs to a 'ship', so does 'cruise'
> I'm trying to select all cabins of cruise N°1 with prices OR nothing if
> there is no price (meaning cabin not available). I want all cabins
> listed, price or no price.
> Also when doing the query I don't have the id_ship, only the id_cruise.
> What is the best way of doing it? UNION or LEFT JOIN? I tried the latter
> without success and am unsure on how do do the former.
Was does "without success" mean? The objective seems to be
straight-forward:
- Select all cabins that belong to the ship that belongs to
the cruise id_cruise.
- Left join that with the prices of the cruise id_cruise.
Tim
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To: pgsql-sql@postgresql.org
Cc: tim@tim-landscheidt.de
Subject: Re: UNION or LEFT JOIN?
In-Reply-To: <m3635wuaic.fsf@passepartout.tim-landscheidt.de>
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