JOIN / ODBC

[Frank Warmerdam]

On 11/22/05, Abe Gillespie <abe.gillespie at gmail.com> wrote:
> I just read the post "can this be done" and then found this:
>
> http://ms.gis.umn.edu/docs/reference/vector_data/VirtualSpatialData
>
> This makes me think it might be possible to join a layer to an ODBC
> table.  Previously I thought it was only possible to join to a DBF.
> Is this possible?  I'd like to join an Access DB to a MapServer layer.

Abe,

It should be possible to join a table from an access
database to feature data using the above mechanisms
as long as the feature data is already read through
ODBC.

You might want to read over some of the caveats with
regard to OGR SQL JOINs at:

  http://www.gdal.org/ogr/ogr_sql.html

Amoung other things, performance will often suffer
using this approach unless you have few features, or
the ODBC datasource is indexed well.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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