Excellent. There are only three columns in the table student: id, name, and room_id. The column id is the identification number of each student in our table, name is the full name of the student. room_id is the id of the room which the student lives in. The room id is, of course, taken from the table room.

If you examine the table student close enough, you'll find out that some students don't have a room assigned to them. Remember this detail – we'll make use of this information later on.

Ok, let's check the last table.