From: | Tomasz Myrta <jasiek(at)klaster(dot)net> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Query m:n-Combination |
Date: | 2008-10-25 07:59:30 |
Message-ID: | gdujl1$150l$1@news.hub.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Ludwig Kniprath napisal 24.10.2008 11:45:
>
> Join-table
> mn_2_r_id mn_2_c_id
> 1 1
> 1 2
> 1 3
> 1 4
> 2 1
> 3 2
> 3 5
> 4 3
> ...
>
> (in real database this relation is an gis-relation with thousands of
> rivers and countries, related by spatial join, but the problem is the
> same...)
>
> I want to know, which river is running through communities 1,2,3 *and* 4?
> You can see the solution by just looking at the data above (only
> "river_1" is running through all these countries), but how to query this
> by sql?
select mn_2_r_id from join_table
where mn_2_c_id in (1,2,3,4)
group by mn_2_r_id having count(*)=4
(4 = how many communities we should find)
--
Regards,
Tomasz Myrta
From | Date | Subject | |
---|---|---|---|
Next Message | Tomasz Myrta | 2008-10-25 10:06:17 | Re: Order by with spaces and other characters |
Previous Message | Tomasz Myrta | 2008-10-25 07:50:39 | Re: How with to emulate function TRANSFORM from Access in Postgress? |