CecileT,
You have asked a specific question and have been given 2 specific responses.
I'd like to know more about your proposed database. What other things are involved?
And what process(es) act on these things?
Customer, Booking, Reservations, Invoices, Rooms...... It isn't often that 2 tables constitute a working database.
You may get some ideas of the scope, the things possibly involved and relationships between those things from these links.
http://www.databaseanswers.org/data_...tels/index.htm ----a data model
http://www.databaseanswers.org/data_...tels/facts.htm ----the facts initiating the model
Good luck with your project.