Personal GDBs: How are feature classes and feature datasets linked?

[AlfredBaldenweck]

Hi all,

Quick question today.

I have a personal GDB with two feature classes living in a feature dataset. 

What I can't figure out is how Arc can figure out that they live there?

There is nothing in the feature class table linking them to the dataset, so how does Arc know?

[JohnPlunkett]

Hello - if you are using Personal Geodatabases. - Can you consider Migrating to the file geodatabase—ArcMap | Documentation (arcgis.com)

This is especially important if you are going to be using ArcGIS Pro as Personal Geodatabases can't be read/used in ArcGIS Pro

To answer your question- 

what do you see in GDB_Items?

[AlfredBaldenweck]

No worries, I am well aware that Pro doesn't do personal geodatabases and am in the process of converting what we have.

More to the point:

I don't have a GDB_Items table.

The only thing that lists all of them (feature classes, feature dataset) is GDB_UserMetadata

This is an .mdb, and ArcMap/Catalog correctly shows them as being inside the feature dataset.

I just opened up another, entirely unrelated MDB and have the same experience.

Why wouldn't they just be linked in a field in the feature class table, like, for example, Spatial reference is?

I'm very confused, here.  

Edit: Apparently it's because these MDBs are from an earlier version. Once upgraded to 10, the items table appears. However, without upgrading them, how can it tell what they belong to?

[AlfredBaldenweck · Accepted solution]

Okay. According to ArcGIS Server for the Java Platform 9.3 Help (esri.com), the feature datasets are linked to feature classes via the GDB_ObjectClasses table.

So, in my test database:

Not sure how far back feature datasets were introduced, but for version 10+, use GDB_Items and for 9 (and maybe earlier) use GDB_ObjectClasses.

Will update this post if I find anything for earlier versions.