[postgis-users] Join variation

[Obe, Regina]

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: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] 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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