|I am trying to create an ER diagram for online auction for smart phones.
The brand new phones are only for sale. The sale is in auction style. A new phone can be listed with a starting price and available numbers etc for a few days (e.g. 3 days). During this period, a buyer can put a bid with an offered price for a listing. At the end of the period, the listing can have a number of bids. Based on the bids of a listing, sale transactions may happen between the sellers and buyers.
2. The used phones are only for rent. A buyer is to submit an application for renting a phone. As a result, rent transactions may happen between sellers and buyers.
3. As described above the customers are either sellers (selling or leasing phones) or buyers (buying new phones or renting the used phones). A seller must have a registered payment method (e.g. PayPal) for the income from selling and a registered payment method (e.g. PayPal) for paying management fees to the Best Deal. A buyer could have a registered payment method (e.g. PayPal) for paying any purchased items or just paying by credit card directly when buying. However either a seller or a buyer must have at least a phone or a mobile or an email contact.
this is what i have done so far..
Photo of ER Diagram[^]