For more, see Data Source Manager, Database Tabs
External data is typically data contained in a database (Access or SQL) that is kept outside of the GIS, like PVA’s TRIM database. The database is linked to the GIS layer by a matching field in the database table.
To View External Data:
Go to Tools, Data Source Manager
Select the layer linked to the external database
The external data should be visible in the table view.
To Link External Data:
Open the Layer Manager dialog
Activate the Setup Data Sources Tool
Select desired layer under Layer Name
Select matching field under Layer Field