The point data set from table points in the Microsoft Access Database (mdb) file data.mdb is visualized as layer points.lyr in ArcMap 10.6. The coordinate system is known. However, it is not allocated yet, i.e. the property of points.lyr says Coordinate System: Undefined. How can I allocate the coordinate system to points.lyr? The tool Data Management Tools > Projections and Transformations > Define Projection works for raster files. However, it seems not to work for a layer file with data from a mdb-file.

Screen-shots from processing and error-message

It is verified that the dataset is neither used by another application, locked nor read-only.

  • It is not clear if you are asking about a personal geodatabase (which is an access database) or a traditional access database created in access itself? Please confirm.
    – Hornbydd
    Jun 4, 2019 at 13:08
  • It looks like it is a GDB.
    – stonebe
    Jun 4, 2019 at 13:20
  • OK so it's a geodatabase. It is still not clear if your points dataset is a featureclass or a simple non-spatial table.
    – Hornbydd
    Jun 4, 2019 at 14:09
  • It looks like it is a featureclass as there is a column called OBJECTID and another column called SHAPE (SHAPE is Long binary-Data for all rows).
    – stonebe
    Jun 4, 2019 at 14:18
  • 1
    So if it is featureclass without a coordinate system then you would typically run the Define Projection tool on that dataset to set it. Which sounds like what you have done. You say it does not work? What is the error message? I would suggest you place that information with a couple of screen shots in your question.
    – Hornbydd
    Jun 4, 2019 at 14:22

1 Answer 1


Looking at your image you are accessing the geodatabase from within MS Access? That is a real no-no! You can easily (if you have not already done it) corrupt the database.

You must only interact with a personal geodatabase from within ArcMap to ensure data integrity. You create personal geodatabases from within Arcmap, you cannot simply convert an existing access database into a personal geodatabase.

At this point no one knows what you've done and how much damage you have done to it.

So assuming its just that point dataset, I would approached as this:

  1. Create a personal geodatabase from ARCMAP
  2. In ARCMAP import your corrupted (?) table into your personal geodatabase as a non-spatial table, so you have ID,X,Y, Other fields...
  3. Create a temporary XY event layer, at this point set coordinate system.
  4. Convert your temporary XY event layer into a FeatureClass by using Copy Features tool.

All this is done inside ArcMap, you never mess around with the geodatabase using Access itself.


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