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camper/revert/campsite_type_pet_cost.sql

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Add campsite_type_pet_cost relation to hold price of dogs in campsites 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.
2024-02-10 05:18:30 +00:00
-- Revert camper:campsite_type_pet_cost from pg
begin;
drop table if exists camper.campsite_type_pet_cost;
commit;