I'm trying to solve an exercise(studying for an exam) concerning auctions and the text is as following:
An auction organization does auctions of various product and wants to have a database that stores all the necessary information to it's appropriate functioning.
In each auction there's a couple of products available for sale.Those products are only put for sale if they are in great conditions.Only people who registered can participate in an auction.In an auction, a person can make many licitations.Each licitation get's registered as an unique identifier.A licitation referes always to one product that was for sale in an auction.At the end of the auction the licitated products are sold to the person whose liciattion value was the highest.We want to store the information about the date,value of the sale and type of payment.
Some of the attributes to register are the following:
Id_person, name,identity card,address;id_auction,date,place of auction; id_product,designation,type and base value;id_licitation and value of licitation;id_sale,value, date of sale and type of payment.
I need some help on this,and this's what I've came so far(see attachment).
Also I have a question: in what cases should we use a ternary relationship?
No,it's not scribbled on a freakin napkin.That's the way we usually draw our diagramas on classes and that's the way the professor usually draw his diagram on classes.But I think I can do a better diagram that can look a bit more clean.