<HTML dir=ltr><HEAD><TITLE>Re: [postgis-users] I'm missing something</TITLE>
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<DIV dir=ltr><FONT face=Arial color=#000000 size=2>Bob,</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial color=#000000 size=2>Strange. I don't think I have ever seen quite that error before. What does</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>SELECT ST_GeometryType(the_geom)</FONT></DIV>
<DIV dir=ltr><FONT face=Arial size=2>FROM tank_lin;</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>give you?</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>Regina</FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> postgis-users-bounces@postgis.refractions.net 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>
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<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 mailing list<BR>>> postgis-users@postgis.refractions.net<BR>>> <A href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</A><BR>>><BR>> _______________________________________________<BR>> postgis-users mailing list<BR>> postgis-users@postgis.refractions.net<BR>> <A href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</A><BR><BR>_______________________________________________<BR>postgis-users mailing list<BR>postgis-users@postgis.refractions.net<BR><A href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</A><BR></FONT></P></DIV></BODY></HTML>
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