Question

You have been hired by a library to design a (simplified) database system to keep track of books in their collection, individual copies of these books, who currently has which copies of which books out on loan, and when they're due to be returned. The library has members, each of whom has a unique card number; a name, consisting of first name and last name; and one or more e-mail addresses. The library has many books, each of which has a unique ISBN, a title, a synopsis, and one or more authors. Each author has a name composed of first name and last name, a dateOfBirth, and a URL. No two authors have the same name and the same dateOfBirth. There may be several copies of a given book. Each copy of a book has a copyNum an aqDate (when the library acquired the copy), and a condition; copies of two different books may have the same copyNum, but two copies of the same book cannot have the same copyNum. The library keeps track of copies of books that members have borrowed, but have not yet returned, and notes the due date for each of these.

Draw an ER diagram modeling this scenario. The diagram should include entity sets (possibly weak entity sets), relationship sets, and all relevant attributes, primary keys, discriminators (if your design has weak entity sets), and any cardinality constraints that follow from the above description.

Answer 1

The ER diagram represents the relationships between the entity sets in the library's database system, including members, books, copies, and authors.

Step-by-step explanation:

ER Diagram for Library Database System

In the library database system, we can identify several entity sets such as Member, Book, Copy, Author, and Loan. The Member entity set includes attributes like card number, first name, last name, and email address. The Book entity set contains attributes like ISBN, title, and synopsis. The Copy entity set includes attributes like copy number, acquisition date, and condition. The Author entity set includes attributes like first name, last name, date of birth, and URL. The Loan entity set includes attributes like due date.

There are several relationship sets in this system. The Member entity set is related to the Loan entity set through the Borrow relationship, indicating that members can borrow books. The Book entity set is related to the Copy entity set through the Has Copy relationship, indicating that each book can have multiple copies. The Book entity set is related to the Author entity set through the Has Author relationship, indicating that each book can have multiple authors.

This ER diagram represents the relationships between the entity sets and the attributes that define each entity set. It provides a visual representation of the library's database system, including the relationships between members, books, copies, and authors.