[postgis-users] Problem in getting geometry data

Obe, Regina robe.dnd at cityofboston.gov
Fri Aug 29 03:32:38 PDT 2008

If you are looking at it in PgAdmin III, it looks empty but isn't.
That's just a limitation of pgadmin.  You also want to order your points
by the way so they go into the make line aggregate in the right order.

To make sure it is not empty do this check - if it returns false then
you are fine, if it returns blank or true then you are not fine.

 SELECT Max(f.ogc_fid) as newgid,ST_IsEmpty(ST_MakeLine(f.wkb_geometry))
As isempty FROM
(SELECT ogc_fid , wkb_geometry FROM track_points where ogc_fid<1000
ORDER BY ogc_fid) AS f

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Sent: Friday, August 29, 2008 6:15 AM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] Problem in getting geometry data

SELECT Max(f.ogc_fid) as newgid,ST_MakeLine(f.wkb_geometry) As newgeom
(SELECT ogc_fid , wkb_geometry FROM track_points where ogc_fid<1020) AS

This gives newgeom only for  ogc_fid<1020. If I omit this constraint or
value above 1020 ,den newgeom column is empty....what can be the
problem..Can any1 suggest something 

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