[postgis-users] Merge all polygons from a dataset

[danny]

Thanks Robert.

I actually exported from ogr2ogr and it created a shape that worked fine in
ArcView.

Best



On Fri, Aug 1, 2008 at 5:19 PM, Burgholzer,Robert <
rwburgholzer at deq.virginia.gov> wrote:

>  Could ArcView perhaps want some columns other than just the shape?
> Perhaps you could put a numeric ID or something else in there.
>
>
>
> Just a thought,
>
>
>
> Robert W. Burgholzer
>
> Surface Water Modeler
>
> Office of Water Supply and Planning
>
> Virginia Department of Environmental Quality
>
> rwburgholzer at deq.virginia.gov
>
> 804-698-4405
>
> Open Source Modeling Tools:
>
> http://sourceforge.net/projects/npsource/
>
> -----Original Message-----
> *From:* postgis-users-bounces at postgis.refractions.net [mailto:
> postgis-users-bounces at postgis.refractions.net] *On Behalf Of *danny
> *Sent:* Friday, August 01, 2008 9:30 AM
> *To:* PostGIS Users Discussion
> *Subject:* Re: [postgis-users] Merge all polygons from a dataset
>
>
>
> Many thanks, Regina! Indeed ST_Union generated the polygon, invisible in
> PgAdmin!!
>
> It creates a nice layer when I open it in uDig.
>
> However when I export it with pgsql2shp, the shape is unreadable by ArcView
> with the errmsg: Number of shapes does not match the number of table
> records.
>
> Here's how I created the layer:
>
> create table europe_contour();
> SELECT addgeometrycolumn('db, 'europe_contour', 'the_geom',
> 32767,'MULTIPOLYGON', 2 );
> insert into europe_contour(the_geom) values( (select st_union(the_geom)
> from europe));
>
> Then I generate the shapefile:
>
> "c:\Program Files\PostgreSQL\8.3\bin\pgsql2shp.exe" -u postgres -P password
> -f europe_contour db europe_contour
>
> Any suggestions perhaps on anything I've wrong?
>
>  On Fri, Aug 1, 2008 at 1:15 PM, Obe, Regina <robe.dnd at cityofboston.gov>
> wrote:
>
> Erik,
>
> How were you using ST_Union and what exactly do you mean by no result.  no
> result as it looks blank?  If you are using something like PgAdmin III - it
> will look blank because it exceeds the buffer supported by PgAdmin III.
>
>
>
> SELECT the_geom is null
>
> FROM (somequery or table) as foo
>
> LIMIT 1
>
>
>
> will tell you if its actually returning no geometry
>
>
>
> Hope that helps,
>
> Regina
>
>
>  ------------------------------
>
> *From:* postgis-users-bounces at postgis.refractions.net [mailto:
> postgis-users-bounces at postgis.refractions.net] *On Behalf Of *danny
> *Sent:* Friday, August 01, 2008 6:12 AM
> *To:* postgis-users at postgis.refractions.net
> *Subject:* [postgis-users] Merge all polygons from a dataset
>
> Hello everybody,
>
> I've converted a shapefile of Europe to PostGIS. I would like to merge all
> the countries together so that I only have one polygon left, the whole
> contour of Europe. I have tried ST_Union that gives me no result. I've tried
> several other functions to no avail. Does anybody know how I should proceed?
>
> Many thanks,
>
> Erik
>    ------------------------------
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