The Data Grid Compare To option was used to open Difference Viewer to compare table data with a TEF file. Data was moved to and from the database table and TEF file. How to make changes to database table using Difference Viewer?
Data Difference Viewer is not designed to make changes and synchronize the database table. Use Data Compare via Tools | Data Compare and Sync menu option to compare and synch using database tables.
TEF files can be opened via File | Open File menu option. Its data can be exported to a Text and XLS file and this file can be imported to a database table. This table can then be used in Data Compare.