EXAMPLE: GOOD READING BOOK STORES

Figure 2.10 shows the E-R diagram for Good Reading Bookstores. Good Reading is a chain of bookstores that wants to keep track of the books that it sells, their publishers, their authors, and the customers who buy them. The BOOK entity has four attributes. Book Number is the unique identifier. A book has exactly one publisher. Publisher Name is the unique identifier of the PUBLISHER entity. A publisher may have (and generally has) published many books that Good Reading carries; however, Good Reading also wants to be able to keep track of some publishers that currently have no books in Good Reading's inventory (note the zero-modality symbol from PUBLISHER towards BOOK). A book must have at least one author but can have many (where in this case “many” m....