Re: UNION or LEFT JOIN?

Louis-David Mitterrand <vindex+lists-pgsql-sql(at)apartia(dot)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