Description:

generates an abstract Database connection class that acts as the interface to the given database

Example:

$ rails generate db_connect <Name of Database>

This will create:
  create  app/models/name_of_database_db.rb
    -----
    class NameOfDatabaseDb < ActiveRecord::Base
      self.abstract_class = true
    ...
    -----

 Inside of which will be the appropriate configuration for that database's ActiveRecord connection.
 All rails models representing tables in that database must inherit from this abstract class.

 -----
 rails model:  app/models/some_table.rb
 -----
    class SomeTable < NameOfDatabaseDb
    ...
 -----