ABF and Vision applications can connect to zero, one, or more database sessions. An application can open an initial session and, with subsequent connect statements, open additional sessions with the same or different databases.

By default, an ABF or Vision application connects on start up to the database from which the application was linked.

You can override the default when you run the application image. Run the image with the -d or -database flag to start the application with a connection to the specified database.

You can also start an application without a database connection, by running the image with the -nodatabase flag. Use the ‑nodatabase flag if the application does not require access to a database, that is, if the application has no database statements, QBF frames, report frames, or uncompiled forms.

If you start the application without a database, you can later connect to a database with 4GL code. The connect statement must precede any statements that access the database.

Using multiple sessions in ABF and Vision applications is similar to using multiple sessions in embedded SQL.