Problem 1. In this exercise, you will design a small database for used textbooks, as might be used by an on-line trading site like Amazon. The database will store textbooks for sale. Each textbook has an ISBN, a catagory (e.g., Math) it belongs to, a name. In addition, status descriptions about the books are maintained. Each book is required to have one such description so that the system can rate it fairly. Each textbook is published by a company in the publishing year. Each publisher has to have published at least some textbooks. Each textbook has one or more sellers, which may be either companies (corporation sellers) or individuals (individual sellers). For each company, the database maintains a name of the company, its address, its phone numbers (could be more than one phone number, each with a number and a description), and its contact person (who is an individual with all the related information for individuals, see next sentence). For each
individual, the database keeps a name, a phone number and an email address. A contact person whose company sells a book cannot be selling the same book as an "individual seller" at the same time (he/she may sell other books as an indiviual seller).
You are required to draw the ER diagram only for above discription following the convention of the textbook. Draw an ER-diagram for the database, identifying the following: (i) all the entity sets; (ii) all the relationship sets and their multiplicity;
(iii) the primary key for each entity set (and weak entity set, if any) and each relationship set.
Indicate which properties in the problem description (if any) are NOT reflected by your design. For each of these properties you give (again, if any), use as an example situation that is allowed by your ERD but this situation contradicts the property in the description.