[GRASS-user] Using Access .mdb Files

John C. Tull jctull at gmail.com
Tue Jan 11 17:05:00 EST 2011

On Jan 11, 2011, at 1:54 PM, Rich Shepard wrote:

> On Tue, 11 Jan 2011, John C. Tull wrote:
>> Did it preserve spatial topology for you? I was able to successfully
>> convert an mdb to sqlite, but it does not have any geographic reference.
>> This is fine for extracting data tables, but seems to sacrifice the value
>> of a spatial database, unless there are fields representing coordinates
>> for each table row.
> John,
>  I've no idea. I'm only unzipping BLM data files now. I assume that Access
> has no topology as it's a flatfile database that could be used as a front
> end to SQL-Server.
>  The file I have is for land status (i.e., ownership) and the SQLite tables
> are:
> sqlite> .tab
> GDB_AnnoSymbols        GDB_GeomColumns        GDB_ReplicasEx GDB_AttrRules          GDB_JnConnRules        GDB_SpatialRefs GDB_CodedDomains       GDB_ObjectClasses      GDB_Subtypes GDB_DefaultValues      GDB_RangeDomains       GDB_Toolboxes GDB_Domains            GDB_RasterCatalogs     GDB_TopoClasses GDB_EdgeConnRules      GDB_RelClasses         GDB_TopoRules GDB_ExtensionDatasets  GDB_RelRules           GDB_Topologies GDB_Extensions         GDB_ReleaseInfo        GDB_UserMetadata GDB_FeatureClasses     GDB_ReplicaDatasets    GDB_ValidRules GDB_FeatureDataset     GDB_ReplicaLog         Ownership GDB_FieldInfo          GDB_Replicas           Ownership_Shape_Index
>  I've no idea what the GDB_ prefix is supposed to mean. The Bureau
> apparently does not have these data on their ESRI GIS or we'd see .shp or
> .e00 files rather than .mdb files.
> Rich

Hi Rich,

Actually, your file is a topological database. I work with this information from the BLM in Nevada regularly. On the Nevada GIS website, they have some of their files in both .mdb and shapefile. I go to the shapefiles because of the very issue you are encountering with a closed file format. Your land status columns are different than the Nevada specific ones, but this particular file is meant to represent the managing agency or ownership status of lands for the area covered. I'm not sure what value the database has without the topology.

Here is the link to the Nevada BLM GIS webpage:


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