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Chapter 7: Problem 3

Consider your educational institution or place of work. 1\. What are some of the entity types that would be useful? 2\. What relationships exist that relate entity types to one another? 3\. What attributes would be useful to describe entities and relationships? 4\. Draw an ERD.

Short Answer

Expert verified
The entities could be Students, Teachers, Courses, and Classrooms. Relationships might be 'teachers teach courses', 'students take courses', 'courses are taught in classrooms'. Attributes could include elements like Student ID, Course Duration, or Classroom Number. The ERD would graphically represent all these elements and their interconnections.

Step by step solution

01

Identify Entity Types

The first step involves identifying the entities. In a school setting, entities could be Students, Teachers, Courses, and Classrooms. Each of these has its unique characteristics.
02

Define Relationships

Next, define relationships between different entities. For instance, Teachers teach Courses, Students take Courses, and Courses are taught in Classrooms. These are all examples of relationships.
03

Identify Attributes

Now, identify attributes for each entity. For example, a Student entity might have attributes like Student ID, Name, and Major. A Course entity might have attributes such as Course ID, Course Name, and Course Duration. The Teacher entity can have attributes like Teacher ID, Name, and Subject Expertise, whereas the Classroom entity might have attributes like Classroom Number and Seating Capacity.
04

Draw the ERD

The ERD should represent entity types with rectangles, relationship types with diamonds, and attributes with ovals. Connect them with lines indicating the relationships. Remember to denote any primary key attributes (like ID numbers) specially, usually with underlining.

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Most popular questions from this chapter

Suppose a company that sells products has a product entity type with the following attributes: prodNum, prodDesc, prodPrice. Suppose all three attributes are single-valued and that prodNum is a key attribute - each product has a different product number. Illustrate this information in an ERD.

A college or university will keep track of several addresses for a student, but each of these can be named differently: for example, consider that a student has a mailing address and a home address. Create an ERD for a student entity type with two composite attributes for student addresses where each comprises several single-valued attributes.

Develop an ERD to support the management of credit cards. Each credit card has a unique number and has a customer associated with it. A customer may have several credit cards. The customer has a first name, last name, and an address. Each time a customer uses a credit card we must record the time, the date, the vendor, and the amount of money involved.

Consider an educational environment where the institution tracks the performance of each student. Often this is called the students overall average, or overall grade point average. Is such an attribute a derived attribute? How is its value determined?

Draw an ERD involving employees and their dependents where each employee has a unique id number and where dependents of the same employee are numbered starting at 1. It may be rare, but we will allow for dependents of the same employee to have the same name and birthdates. Include typical attributes for an employee, and for a dependent include the birthdate, first and last names.
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