raise_for_multi_db

# File activerecord/lib/active_record/tasks/database_tasks.rb, line 156
      def raise_for_multi_db(environment = env, command)) # :nodoc:
        db_configs = configs_for(env_name: environment)

        if db_configs.count > 1
          dbs_list = []

          db_configs.each do |db|
            dbs_list << "#{command}:#{db.name}"
          end

          raise "You're using a multiple database application. To use `#{command}` you must run the namespaced task with a VERSION. Available tasks are #{dbs_list.to_sentence}."
        end
      end