UltraLite User's Guide
UltraLite Features and Limitations
Each table in your UltraLite application must include a primary key.
The UltraLite generator uses primary keys from your reference database to generate primary keys in the UltraLite database. If the primary key columns for any table are not included in the data required in the UltraLite database, the UltraLite generator looks for a uniqueness constraint on the table, and promotes the columns with such a constraint to a primary key in the UltraLite database. If there are no unique columns, the generator reports an error.
Primary keys are required not only for UltraLite applications, but also during MobiLink synchronization, to associate rows in the UltraLite database with rows in the consolidated database.