Regina,
Thank you! I thought this was a LEFT JOIN situation, but my brain just
was not parsing the problem. I used the 2nd query and it seems to be
working great.
I'm runnning an older version:
"POSTGIS="1.1.1" GEOS="2.2.1-CAPI-1.0.1" PROJ="Rel. 4.4.9, 29 Oct 2004"
USE_STATS"
"PostgreSQL 8.1.8 on x86_64-pc-linux-gnu, compiled by GCC cc (GCC) 3.3.5
(Debian 1:3.3.5-13)"
So I dropped the "ST_", but I am getting a NOTICE:
NOTICE: LWGEOM_gist_joinsel called with incorrect join type
CONTEXT: SQL statement "select a.file, a.id, a.name
from points a LEFT JOIN polygons b
ON (a.the_geom && b.the_geom and distance(a.the_geom, b.the_geom) =
0.0)
where b.the_geom IS NULL"
Do you know why? Is this something that I need to worry about?
Your most excellent support of this list is always noticed by this
reader. Thank you.
Best regards,
-Stephen Woodbridge
Obe, Regina wrote:
SELECT a.*
FROM point a LEFT JOIN polygons b
ON (a.the_geom && b.the_geom
and ST_distance(a.the_geom, b.the_geom) = 0.0)
WHERE b.the_geom IS NULL
or
SELECT a.*
FROM point a LEFT JOIN polygons b
ON ST_Within(a.the_geom, b.the_geom)
WHERE b.the_geom IS NULL
I think the second one should be more efficient, but I haven't done any
benchmarks.
Hope that helps,
Regina
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Stephen Woodbridge
Sent: Wednesday, January 23, 2008 10:27 PM
To: PostGIS Users Discussion
Subject: [postgis-users] Spatial query Help: points not in set of
polygons
Hi all,
I'm drawing a blank on setting up a query for this.
I have a tables points and a table of polygons. I need to find all the
points that are not in any of the polygons.
select a.*
from points a, polygons b
where a.the_geom && b.the_geom
and distance(a.the_geom, b.the_geom) > 0.0;
The problem with this is that if a point is in polygon A it will have a
distance to polygon B, so this in no good.
I thought of doing something like:
select * from points
where distance(the_geom, union((select the_geom from polygons))) >
0.0;
or
select * from points
where distance(the_geom, collect((select the_geom from polygons))) >
0.0;
So is there a better way to do this. Seems like there should be. If not
which of these would you suggest.
Thanks,
-Steve
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