Hi Rogrigo
What Sergio is trying to say here is something like this:
1. You can have 3 different Rails apps for this, with 3 different databases. And then for the admin app, you can connect to the client app and company app database and pull information from there. For this, you will have to specify two other databases in your database.yml file, one with connection details of client app database and another with connection details for company app database.
Then either you can direct do sql queries on those databases or define corresponding models for the related tables in your admin app, and ask them to connect to right database. Using something like this in the model - "establish_connection 'company_database' "
2. Have 3 different Rails apps but use the same database for all three. Then you directly have access to all the company and client data in your admin app as well.