Question

For each of the following descriptions: - Identify the degree and cardinalities of the relationship. - Draw the corresponding E-R diagram. Don’t forget the degree and cardinalities of each relationship.

1 . A book is identified by its ISBN number, and it has a title, a price, and a date of publication. It is written by one or multiple authors. Each author is identified by an author number and has a name and date of birth. Each author has either one or multiple books. Occasionally, it is possible that prospective authors who have not yet published any books.

2. The book described above can be part of a set, which is also identified as a book and has its own ISBN number. One book can belong to several sets, and a set consists of at least one but potentially many books

3. A piano manufacturer wants to keep track of all the pianos it makes individually. Each piano has an identifying serial number and a manufacturing completion date. Each piano represents exactly one piano model, all of which have an identification number and a name. The manufacturer usually produces several pianos from a single model and each model is used to make at least one piano. A piano model is created by a single designer. It is important for the manufacturer to maintain information about the designer name and identifying them using an identification number. Note that while a designer can send multiple model to the manufacturer, some of the designers stored in the database have not sent any model yet.

Answer 1

1 . A book is identified by its ISBN number, and it has a title, a price, and a date of publication. It is written by one or multiple authors. Each author is identified by an author number and has a name and date of birth. Each author has either one or multiple books. Occasionally, it is possible that prospective authors who have not yet published any books.

This relationship is a degree of 2 (binary). This relationship is One-to-Many from Publisher to Book

2. The book described above can be part of a set, which is also identified as a book and has its own ISBN number. One book can belong to several sets, and a set consists of at least one but potentially many books

This relationship is a degree of 1 (unary). This relationship is Many-to-Many

This solution assumes that “series” and “sets” are synonymous terms. The question does not require that a series have any special attributes or distinguishing features, so it can be represented in the data model like any other Book instance and identified by ISBN.

3. A piano manufacturer wants to keep track of all the pianos it makes individually. Each piano has an identifying serial number and a manufacturing completion date. Each piano represents exactly one piano model, all of which have an identification number and a name. The manufacturer usually produces several pianos from a single model and each model is used to make at least one piano. A piano model is created by a single designer. It is important for the manufacturer to maintain information about the designer name and identifying them using an identification number. Note that while a designer can send multiple model to the manufacturer, some of the designers stored in the database have not sent any model yet.

These relationships have a degree of 2 (binary). These relationships are One-to-Many