From: | Louis-David Mitterrand <vindex+lists-pgsql-sql(at)apartia(dot)org> |
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To: | pgsql-sql(at)postgresql(dot)org |
Subject: | UNION or LEFT JOIN? |
Date: | 2010-02-16 14:08:14 |
Message-ID: | 20100216140814.GA22577@apartia.fr |
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Lists: | pgsql-sql |
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.
Thanks,
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