I tried this -
Insert into graphics.process_dgm(the_geom)
Select ST_Union(the_geom)
from tank_lin;
and got the error "Unknown geometry type: 0"
Bob
----- Original Message -----
From: "Paul Ramsey" <[EMAIL PROTECTED]>
To: "PostGIS Users Discussion" <[email protected]>
Sent: Tuesday, May 20, 2008 9:51 AM
Subject: Re: [postgis-users] I'm missing something
You don't want the GROUP BY. It is grouping the union op on distinct
geometry... ie, one per row. Remove it and you'll get what you want,
one output row.
P
On Tue, May 20, 2008 at 8:49 AM, Bob Pawley <[EMAIL PROTECTED]> wrote:
Hi
I am attemptijng to use the ST_Union function to collapse three rows from
a
table called tank_lin into one row in table called process_dgm.
Here's what I used -
Insert into graphics.process_dgm(the_geom)
Select ST_Union(the_geom)
from tank_lin
Group by tank_lin.the_geom;
The result is three rows inserted into process_dgm, each row appearing to
be
simple copies of each of the original rows.
I also attempted group by another column but received error 'unknown
geometry'.
I also tried STR_LineMerge with similar results.
What am I not considering?
Bob
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