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<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>Not quite clear what you are trying to
do</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>1) Do you have table a with n rows and table b with m rows
(each having the same fields) and you want table c with (m + n)
rows.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>This is a regular old SQL union and not a spatial union
</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>So would be done with</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>INSERT INTO c(field1,field2, ..,
the_geom)</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>SELECT a.field1, a.field2, ...
a.the_geom</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>FROM a</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>UNION ALL</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>SELECT b.field1, b.field2, ...
b.the_geom</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><FONT face=Arial
color=#0000ff size=2>FROM b;</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>or are you trying to do a
spatial union or intersection and in what case what records are you trying to
group together into a geometry or join by</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>There are so many
permutations of spatial unions and spatial intersections - that its hard to give
an answer without having more details about what you are trying to
accomplish.</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>e.g a spatial
intersection result may looks something like this</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>2) </SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008><SPAN
class=792315312-26032008><FONT face=Arial color=#0000ff size=2>INSERT INTO
c(field1,field2, field3,.., the_geom)</FONT></SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>SELECT a.field1,
a.field2, b.field1 as field3 .. ST_Intersection(a.the_geom, b.the_geom) as
the_geom</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>FROM a INNER JOIN b on
(a.zip = b.zip (or whatever field) and ST_Intersects(a.the_geom,
b.the_geom)</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=792315312-26032008>Hope that
helps,</SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=792315312-26032008>Regina</SPAN></DIV></FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <B>On Behalf Of </B>K.
Pandey<BR><B>Sent:</B> Tuesday, March 25, 2008 11:51 PM<BR><B>To:</B>
postgis-users@postgis.refractions.net<BR><B>Subject:</B> [postgis-users] Spatial
Analysis/Union of shapefiles<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>I want to perform union of two shape files using postgresql.</DIV>
<DIV>I converted the shape files to postgres tables using shp2pgsql
utility.</DIV>
<DIV>How to perform the union/intersection of these two tables.</DIV>
<DIV>Once the union/intersection is completed, I can convert the union file back
to shapefile using pgsql2shp utility.</DIV>
<DIV> </DIV>
<DIV>-- <BR>Kamal Pandey<BR>Dehradun </DIV></BODY></HTML>
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