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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