[Mapserver-users] OGR layer and JOIN {Scanned}

[Frank Warmerdam]

Siki Zoltan wrote:
> Hi list,
> 
> Is it possible to JOIN a dbf file to an OGR layer?
> Is there any case rule (lower/uppercase) for column names?
> Somewhere in the docs/wiki I read uppercase sould be used.
> It is not true for OGR layers, I must use the same case as in the
> original table definition.
> I failed to connect a mapinfo tab to a dbf file. In the query
> result I got [column_name] instead of the value. Can you chek my try?

Siki,

I don't know anything about the JOIN operation done by MapServer.  I just
wanted to mention that there is also an option to let OGR do the join.  However,
that can be very slow unless the secondary table is effectively indexed on
the index column.  This can be done for a .dbf file.

There is some discussion of joins in OGR SQL in this document:
   http://www.remotesensing.org/gdal/ogr/ogr_sql.html

There is a topic in the wiki talking about how you can use .ovf files to
encapsulate an SQL from an OGR datasource for use in MapServer.

Hopefully others will be able to more directly address how in-MapServer
joins work.

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