Revision: | $Revision: 8472 $ |
---|---|
Date: | $Date: 2009-01-28 13:08:43 -0800 (Wed, 28 Jan 2009) $ |
Author: | David Fawcett |
Contact: | david.fawcett at moea.state.mn.us |
Contents
This method takes advantage of OGR’s MySQL driver and avoids the need to set up an ODBC connection.
This is the primitive MySQL support for point data, not the recently added MySQL spatial support found in GDAL/OGR 1.3.2 .
Support for this functionality is found in GDAL/OGR 1.2.6 and older on Windows and GDAL/OGR 1.3.2 on Linux.
The MySQL wiki page might contain additional information.
Needed
Here is the .ovf file named aqidata.ovf
<OGRVRTDataSource>
<OGRVRTLayer name="aqidata">
<SrcDataSource>MYSQL:aqiTest,user=uuuuu,password=ppppp,host=192.170.1.100,port=3306,tables=testdata</SrcDataSource>
<SrcSQL>SELECT areaID, x, y, sampleValue FROM testdata</SrcSQL>
<GeometryType>wkbPoint</GeometryType>
<GeometryField encoding="PointFromColumns" x="x" y="y"/>
</OGRVRTLayer>
</OGRVRTDataSource>
If you look at the connection string in <SrcDataSource>
Use the GeometryField element to tell OGR which fields store the x and y coordinate data. Mine are simply named x and y.
# usr/local/bin/ogrinfo /maps/aqidata.ovf
ogrinfo returns
ERROR 4: Update access not supported for VRT datasources.
Had to open data source read-only.
INFO: Open of `/maps/aqidata.ovf'
using driver `VRT' successful.
1: aqidata (Point)
Don’t worry about the error, this is just telling you that it is a read-only driver. If it really bugs you, call ogrinfo with the -ro (read only) flag.
To see the actual data
# usr/local/bin/ogrinfo /maps/aqidata.ovf -al
LAYER
NAME "MyAqi"
STATUS DEFAULT
TYPE POINT
CONNECTIONTYPE OGR
CONNECTION "aqidata.ovf"
DATA "aqidata"
CLASS
NAME "MyClass"
STYLE
SYMBOL 'circle'
SIZE 15
COLOR 0 255 0
END
END
END
DATA in the LAYER definition should be the same as the name attribute of the OGRVRTLayer element in the ovf file.
For this to draw, you need to have a SYMBOLSET defined in your mapfile and have a symbol called ‘circle’ in your symbols.sym file.