I need the campsite_id in booking to know what row to show the booking
at. Besides the need of knowing which actual campsite has been booked,
of course.
This field is nullable because we can not now it until an employee has
confirmed the booking; until that point we only know the campsite type
customer requested. I do not care much if the campsite_id is from a
different campsite_type, because maybe the customer requested the change
by phone or what have you, therefore the database can not be that
strict. It must have a value if the booking is confirmed.
It helps me if the arrival_date and departure_date is a single
daterange, because then i can use `&&` and other range operators to work
with these dates. For instance, i have to intersect it with the range
displayed on the screen in order to know which day i have to put it.
But then i have to know whether the booking begins and ends in the
display range, because i only have to show arrival and departure (i.e.,
the box half-way within the first or last boxes) on these days only.
