A string specifying a database user ID. The default value is a null reference (Nothing in Visual Basic).
User IDs are case-insensitive.
Databases are initially created with a single authenticated user named DBA.
If both the user ID and password are not supplied, the user DBA with password sql are used. To make the database more secure,
change the user DBA's password or create new users (with the ULConnection.GrantConnectTo method) and remove the DBA user (with
the ULConnection.RevokeConnectFrom method).