[Chameleon] Multiple DSN Problem

D'cruz,Steven [Ontario] Steven.D'Cruz at ec.gc.ca
Mon Jul 19 14:55:34 EDT 2004

Hi there,

	I was wondering if anyone has any experience with executing
select statements using two different DSNs simultaneously.  For my work,
I require functionality similar to the following: "select a.* from
tablename1 a, tablename2 b where a.id=b.id and b.filter='t'" , where
tablename1 and tablename2 are from 2 DIFFERENT DSNs.  Both DSNs are to
be accessed via a realtime connection to a MS Access 2000 database from
a linux host via the FREETDS drivers.  I currently have both DSNs
working independently in 2 test layers (with no errors) using the
required fields.  Here's the .ovf file used for the selection queue from
the MS Access 2000 databases.

        <OGRVRTLayer name="Layer1Name">
<SrcDataSource>ODBC:UserName/Password at DSN1Name</SrcDataSource>
                <SrcSQL>select statement here</SrcSQL>
                <GeometryField encoding="PointFromColumns" x="longitude"

        <OGRVRTLayer name="Layer2Name">
<SrcDataSource>ODBC:UserName/Password at DSN2Name</SrcDataSource>
                <SrcSQL>select statement here</SrcSQL>
                <GeometryField encoding="PointFromColumns" x="longitude"

What I require is a .ovf file which allows for 2 SrcDataSource(s).  I've
attempted to add an additional <SrcDataSource> tag followed by the
connection information to the second database to the first .ovf file,
however I consistently get no points found... even if I don't use the
data.  Are there any known ways of accomplishing this task?  If not,
I'll probably have to extract the necessary fields from Layer2 in a file
on the local machine, and then use either javascript or php to filter
the results from Layer1.  Any comments, suggestions, and related
questions would be greatly appreciated.  Also, as I'm unsure whether
this would be considered more of a Chameleon or Mapserver problem, I've
posted it to both mailing lists.
Steven D'Cruz
Steven.D'Cruz at ec.gc.ca
(GIS) Web Developer
Environment Canada

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