I need to create a conceptual and logical (normalized) models of parking house according to the requirements below. It looks to me as a very simple concept that doesn't need all tables to have relationships - but then they could not be modelled as entities. I tried asking this on stackoverflow but got no feedback for couple of days now.
Three possible methods of payment:
- a ticket paid on leave,
- prepaid card with cash credit,
- prepaid card with "time credit",
Price of ticket depends on time:
- 1-2hrs = $0,
- 3hrs = $2,
- 4hrs = $4,
- afterwards x hrs = $(x+1), but max. $20 for 24hrs (... easiest to put these to 24 rows, right?).
A ticket (a) may be allowed a 20% discount (ie. for shopping in the mall).
- Cash credit card uses same prices as tickets but with 40% discount.
- Cash credit card can be reloaded.
- Time card is paid once and allows parking while valid.
The problem is I don't know how to put those highlighted relations to the logical db model and whether event to put them there. Is it ok-practice to have isolated tables in the design?