NHibernate Bag Mapping

<bag name="rooms" table="tb_calEvent_rooms" lazy="false">
  <key column="calEventID"/>
  <many-to-many class="BasicRoom" column="roomID"/>
</bag>

public class BasicRoom
{
    private long _id;
    private long _buildingID;
    private string _roomName;

SELECT *
FROM
  dbo.tb_calEvent_rooms
  INNER JOIN dbo.tb_calEvents ON (dbo.tb_calEvent_rooms.calEventID = dbo.tb_calEvents.id)
  INNER JOIN dbo.tb_rooms ON (dbo.tb_calEvent_rooms.roomID = dbo.tb_rooms.id)
  INNER JOIN dbo.tb_buildings ON (dbo.tb_rooms.buildingID = dbo.tb_buildings.id)
WHERE
  dbo.tb_buildings.id = 54

SELECT *
FROM
  dbo.tb_calEvents
  INNER JOIN dbo.tb_calEvent_rooms ON (dbo.tb_calEvents.id = dbo.tb_calEvent_rooms.calEventID),
  dbo.tb_buildings
WHERE
  dbo.tb_buildings.id = 54

<bag name="rooms" table="tb_calEvent_rooms" lazy="false">
  <key column="calEventID"/>
  <many-to-many class="BasicRoom">
    <column name="roomID"/>
    <column name="buildingID"/>
  </many-to-many>
</bag>