Hi Regina,
this gave me the result, but there are lot of overlapping polygons.
Is there any more syntax (keywords) to ask system to polygonise such that there
are no overlapping polygons.
cheers
Ravi Kumar
"Obe, Regina" <[EMAIL PROTECTED]> wrote: First I would call your field
something other than geometry since that is confusing and could get you into
trouble since its a psuedo keyword
So would be something like
DROP TABLE abc
CREATE TABLE abc(code smallint, info smallint, the_geom geometry) with oids
(you might want to use addgeomtrycolumn to create the_geom field so
geometry_columns table is updated, but I'm not sure what you are expecting for
a geometry so not sure what parameters to feed you but would be something like
this.
CREATE TABLE abc(code smallint, info smallint) with oids;
SELECT AddGeometryColumn('public', 'abc', 'the_geom', 4326, 'MULTIPOLYGON',
2);
--The insert
INSERT INTO abc(code, info, the_geom)
SELECT newtb.code, newtb.info, geomunion(newtb.cgeom) as thenewgeom
FROM
( SELECT a.code, b.info, geomunion(a.geometry, b.geometry) as cgeom
FROM a
INNER JOIN b ON a.geometry && b.geometry AND intersects(a.geometry,
b.geometry)
UNION ALL
SELECT a.code, null As info, a.geometry as cgeom FROM a
LEFT JOIN b ON a.geometry && b.geometry AND intersects(a.geometry,
b.geometry)
WHERE b.geometry IS NULL
UNION ALL
SELECT null as code, b.info, b.geometry as cgeom
FROM b LEFT JOIN a ON a.geometry && b.geometry AND
intersects(a.geometry, b.geometry)
WHERE a.geometry IS NULL
) AS newtb
GROUP BY newtb.code, newtb.info
---------------------------------
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of RAVI KUMAR
Sent: Thursday, September 13, 2007 8:17 AM
To: postgis
Subject: [postgis-users] Join variation
Hi Andreas and Regina,
I have used the following to get a result which will have polygons that do not
overlap.
But failed.
Pl help me and correct the following query.
All I want is that after UNION of two layers, the polygons must split and have
both the attributes of source layers. (NO PLace for overlapping polygons)
drop table abc;
create table abc (code smallint, info smallint, geometry geometry) with oids;
insert into abc (select a.code, b.info,(geomunion(a.geometry,
b.geometry)) AS abc FROM b inner JOIN a ON (a.geometry && b.geometry AND
intersects(a.geometry, b.geometry)));
I can actually send two small shape files 'a' and 'b' If U want to private
mail Ids..
Along with the result I wish to get..
Cheers
Ravi Kumar
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