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<DIV><FONT size=2 face=Arial>Hi Regina</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>It gives me three rows each with the expression
"ST_MultiLineString" with nothing else.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Bob</FONT></DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=robe.dnd@cityofboston.gov
href="mailto:robe.dnd@cityofboston.gov">Obe, Regina</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=postgis-users@postgis.refractions.net
href="mailto:postgis-users@postgis.refractions.net">PostGIS Users
Discussion</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, May 20, 2008 10:56
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: [postgis-users] I'm missing
something</DIV>
<DIV><BR></DIV>
<DIV dir=ltr id=idOWAReplyText82919>
<DIV dir=ltr><FONT color=#000000 size=2 face=Arial>Bob,</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT color=#000000 size=2 face=Arial>Strange. I don't think I
have ever seen quite that error before. What does</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT size=2 face=Arial>SELECT
ST_GeometryType(the_geom)</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial>FROM tank_lin;</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT size=2 face=Arial>give you?</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT size=2 face=Arial>Regina</FONT></DIV></DIV>
<DIV dir=ltr><BR>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> <A
href="mailto:postgis-users-bounces@postgis.refractions.net">postgis-users-bounces@postgis.refractions.net</A>
on behalf of Bob Pawley<BR><B>Sent:</B> Tue 5/20/2008 1:07 PM<BR><B>To:</B>
PostGIS Users Discussion<BR><B>Subject:</B> Re: [postgis-users] I'm missing
something<BR></FONT><BR></DIV>
<DIV>
<P><FONT size=2>I tried this -<BR><BR>Insert into
graphics.process_dgm(the_geom)<BR> Select
ST_Union(the_geom)<BR> from tank_lin;<BR><BR>and got the error "Unknown
geometry type: 0"<BR><BR>Bob<BR>----- Original Message -----<BR>From: "Paul
Ramsey" <pramsey@cleverelephant.ca><BR>To: "PostGIS Users Discussion"
<postgis-users@postgis.refractions.net><BR>Sent: Tuesday, May 20, 2008
9:51 AM<BR>Subject: Re: [postgis-users] I'm missing something<BR><BR><BR>>
You don't want the GROUP BY. It is grouping the union op on distinct<BR>>
geometry... ie, one per row. Remove it and you'll get what you want,<BR>>
one output row.<BR>><BR>> P<BR>><BR>> On Tue, May 20, 2008 at 8:49
AM, Bob Pawley <rjpawley@shaw.ca> wrote:<BR>>>
Hi<BR>>><BR>>> I am attemptijng to use the ST_Union function to
collapse three rows from<BR>>> a<BR>>> table called tank_lin into
one row in table called process_dgm.<BR>>><BR>>> Here's what I
used -<BR>>> Insert into graphics.process_dgm(the_geom)<BR>>>
Select ST_Union(the_geom)<BR>>> from tank_lin<BR>>>
Group by tank_lin.the_geom;<BR>>><BR>>> The result is three rows
inserted into process_dgm, each row appearing to<BR>>> be<BR>>>
simple copies of each of the original rows.<BR>>> I also attempted group
by another column but received error 'unknown<BR>>>
geometry'.<BR>>><BR>>> I also tried STR_LineMerge with similar
results.<BR>>><BR>>> What am I not
considering?<BR>>><BR>>> Bob<BR>>>
_______________________________________________<BR>>> postgis-users
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