how to assign a value to several others

I am creating a table to go into a database for a hotel
In order to sort my database each guest is assigned a customer_id
each booking is also assigned a booking_id
I need to create a table which shows the booking_id and the guest_id, and i'm not sure the best way to do this without going through hundreds of individual rows, as some guests can have more than 1 booking_id

Any help would be appreciated

Thanks