Web Mapping Illustrated

Name

VirtualSpatialData (ODBC/OVF)

Synopsis

This is an OGR extension to MapServer. It allows you to connect to databases that don't explicitly hold spatial data, as well as flat text files. Your data must have an x and a y column, and the data may be accessed through an ODBC connection or a direct pointer to a text file.

Types of databases

The VirtualSpatialData OGR extension has been tested with the following databases and should, in theory, support all ODBC data sources.

• Oracle

• MySQL

• SQL Server

• Access

• PostgreSQL

Types of flat files

Comma, tab, or custom delimited text/flat files work with VirtualSpatialData.

Create the data source name (DSN)

Specific notes about creating a DSN on Windows and Linux can be found by searching the MapServer reference documents site at http://mapserver.gis.umn.edu/doc.

On some Windows systems you must create a SYSTEM DSN.

Test your connection

Test your connection with ogrinfo. The syntax for this command is:

    > ogrinfo ODBC:user/pass@DSN table

ogrinfo examples

Here's an example that accesses a comma-separated text file through ODBC; it's a flat text file coal_dep.txt containing lat/long points:

    unknown,na,id,id2,mark,coalkey,coalkey2,long,lat
    0.000,0.000,1,1,7,87,87,76.90238,51.07161
    0.000,0.000,2,2,7,110,110,78.53851,50.69403
    0.000,0.000,3,3,3,112,112,83.22586,71.24420
    0.000,0.000,4,4,6,114,114,80.79896,73.41175

If the DSN name is Data_txt, the ogrinfo command to see a list of applicable files in the directory is:

    > ogrinfo ODBC:jeff/test@Data_txt INFO: Open of `ODBC:jeff/test@Data_txt' ...