Handling of Resources, Roles and User

Hi everyone - In IRIS we would like to arrange the access of two users in such a way that each has access to exactly one (his) database only. Which resource does this (%DB_%DEFAULT allows each of the two users access to both databases). If you create new resources (%DB_Database1 and %DB_Database2) and then add them to individual roles (each for the user to), the access for the users, for example, via a REST client does not give the desired separation (instead once Ok, other database 401 Unauthorized both OK). Is there something special to consider or a special resource that could do this or ...? Thank you very much for any tip.