query.rb

    def stats( params )
      params = params.with_indifferent_access
      group_by = params[:group_by] || 'week'
      cruise_name = params['cruise_name']
      query = "SELECT cruises.name,
                  DATE_TRUNC('#{group_by}', tours.departure) AS #{group_by},
                  COUNT(enquiries.id) AS count_enquiries,
                  SUM(enquiries.pax) AS count_paxes, 
                  SUM(CASE WHEN enquiries.booking_status='Confirmed' THEN enquiries.pax END) AS count_confirmed_paxes
               FROM cruises
                 INNER JOIN enquiries ON cruises.id = enquiries.cruise_id
                 INNER JOIN tours ON enquiries.tour_id = tours.id\n"
               cruise_name.present? ? query += "WHERE cruises.name = '#{ cruise_name }'\n" : ""
               query += "GROUP BY #{group_by}, cruises.name ORDER BY week;"
   
      ActiveRecord::Base.connection.execute( query )
    end