Thanks  everyone!

Från: postgis-users [mailto:[email protected]] För didier 
peeters
Skickat: den 4 juli 2019 14:46
Till: PostGIS Users Discussion
Ämne: Re: [postgis-users] creating points from polygons, storing all attributes

That’s because you named the new geometry « the_geom » like the old one, and 
using « * » gets you all the attributes including « the_geom » .  So either you 
list all the attributes you want to keep in the SELECT instead of using the « * 
» like this :

CREATE TABLE NewPointLayer AS
SELECT attr1, attr2, attr3, attr4, 
ST_PointOnSurface(the_geom)::geometry(Point,32632) AS the_geom
FROM OldPolygonLayer

, or you use another name for your new geometry and you drop the old geometry 
afterward (if you don’t want to have these 2 different geometry columns in your 
new table), like this :

CREATE TABLE NewPointLayer AS
SELECT *, ST_PointOnSurface(the_geom)::geometry(Point,32632) AS geom
FROM OldPolygonLayer ;

ALTER TABLE NewPointLayer
DROP COLUMN the_geom;

Didier


Le 4 juil. 2019 à 14:26, [email protected]<mailto:[email protected]> a écrit :

Thanks, I’ve tried that but get this error:
ERROR: column "the_geom" is specified more than once SQL state: 42701
/Paul

Från: postgis-users [mailto:[email protected]] För Derek 
Watling
Skickat: den 4 juli 2019 13:55
Till: PostGIS Users Discussion
Ämne: Re: [postgis-users] creating points from polygons, storing all attributes

CREATE TABLE NewPointLayer AS SELECT *, 
ST_PointOnSurface(the_geom)::geometry(Point,32632) AS the_geom FROM 
OldPolygonLayer

From: postgis-users 
<[email protected]<mailto:[email protected]>>
 On Behalf Of [email protected]<mailto:[email protected]>
Sent: Thursday, 04 July 2019 13:47
To: [email protected]<mailto:[email protected]>
Subject: [postgis-users] creating points from polygons, storing all attributes

Hi,
I would like to create a point table from a polygon table. One point in each 
polygon
Query = CREATE TABLE NewPointLayer AS SELECT 
ST_PointOnSurface(the_geom)::geometry(Point,32632) AS the_geom FROM 
OldPolygonLayer

But how do I write the query to get all the attributes from OldPolygonLayer to 
the NewPointLayer?

Thanks in advance,
Paul


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