This is required by law.
I do not know why i have this value and the tax amount in the database,
but the payment percent and the number of days are hardcoded. I guess i
am such an inconsistent mess.
It is a separate relation, instead of having a field in campsite_type,
because not all campsite types allow dogs. I could have added a new
field to campsite_type, but then its values it would be meaningless for
campsites that do not allow dogs, and a nullable field is not a valid
solution because NULL means “unknown”, but we **do** know the price —
none.
A separate relation encodes the same information without ambiguities nor
null values, and, in fact, removed the dogs_allowed field from
campsite_type to prevent erroneous status, such as a campsite type that
allows dogs without having a cost — even if the cost is zero, it has to
be added to the new relation.
Customer told us that the minimum number of nights is per campsite type,
not per season. And he wants this, along with the maximum number of
nights, in order to limit the range of departure dates that guests can
choose when booking.