What are the id of all the objects belonging to the transportation class?
id of all the objects belonging to the transportation class refers to OBJ_CLASS_ID and OBJ_CLASS IN ('bus', 'train', 'aeroplane', 'car', 'etc.')
SELECT OBJ_CLASS_ID FROM OBJ_CLASSES WHERE OBJ_CLASS IN ('bus', 'train', 'aeroplane', 'car', 'etc')