Arnd Wippermann wrote:
Hello,
I have an Access DB to hold the geometry as WKT-String and attributes of a
line layer and use OGR with ODBC to display my features.
GEOLINES the line geometry as WKT-String
GEOLINES_TREPPE the attributes for the lines
GEOMETRY_COLUMNS the configuration of table, objecttyp and srs
I have no problem with
CONNECTIONTYPE OGR
CONNECTION 'ODBC:GEOOBJEKT,GEOLINES'
to display my lines on the map.
But I want to classify my lines with values from the table GEOLINES_TREPPE.
In Access the following query delivers what I expect:
SELECT * FROM GEOLINES LEFT JOIN GEOLINES_TREPPE ON GEOLINES.ID_GEOOBJEKT =
GEOLINES_TREPPE.ID_GEOOBJEKT;
When I use this query for my GEOLINES layer in a mapfile and add the
DATA-line, nothing will display and also no error message is given.
Arnd,
I believe the problems is that the ODBC driver does not know what column
in your select result to use as the geometry since it finds this in
the GEOMETRY_COLUMNS table. But this mechanism only works for simple
tables, not custom selects.
One option might be to use a VRT wrapper for the ODBC datasource to
accomplish this instead of trying to use GEOMETRY_COLUMNS.
Best regards,
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