>On one application if my user is on the level 1 her database is oracle and if is level is 2 her database is SQL Server
>
>How can i do ?

With 2 DBCs. Put duplicated DBCs, tables, etc. in 2 different directories. Duplicate all the views [same names, etc.]. The exception would be the connection name. This way, all your forms need no modifications. All you do is open the proper DBC at startup.