Your query looks fine. You know the geometry field is empty how? Did you run select st_npoints(the_geom), or ST_GeometryType(the_geom) from it?
P On Wed, Sep 19, 2012 at 10:57 AM, Nenad Nikolic <nnikoli...@gmail.com> wrote: > As the subject suggests I need to create Linestrings by connecting Points.I > have one table locations that looks like this: > > CREATE TABLE locations > ( > userid integer NOT NULL DEFAULT 0, > "time" integer NOT NULL DEFAULT 0, > "timestamp" bigint, > the_geom geometry(Point,4326), > CONSTRAINT locations_pkey PRIMARY KEY (userid , "time" ) > ) > > Basically it's a table with a lot of locations with Point geometries. Field > 'time' is relative timestamp, from 0 to 179. So for every "userid" there is > 180 entries with 180 locations. > > > What i need to do here is to create a new table which will have one > Linestring per "userid", which was calculated from Points in locations > table, of course in correct order defined in "time" attribute. So new table > should look like this: > > CREATE TABLE trajectories ( > userid int NOT NULL default '0', > the_geom geometry(Linestring, 4326), > PRIMARY KEY ( userid ) > ) > > I can't find a way to do that. Is it even possible to connect multiple > points (in this problem 180 of them) to one Linestring with st_makeline? > > I tried something like this > > SELECT St_MakeLine(the_geom) as the_route, bp.userid > FROM (SELECT userid, the_geom, "time" > FROM locations > ORDER BY "time") bp > GROUP BY bp.userid > ORDER BY bp.userid; > > But result has geometries field empty... > > > > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
