Dbm Chapter 1 Exercises and Problems 1-5

Student:

Class: Database Management

Instructor:

Assignment: Chapter 1

5 Problems/Exercises

Chapter 1 The Database Environment and Development Process

5 out of 22 Problems and Exercises:

1. Problem and Exercise # 1. For each of the following pairs of related entities, indicate whether (under typical circumstances) there is a one-to-many or a many-to-many relationship. Then, using the shorthand notation introduced in the text, draw a diagram for each of the relationships.

Relationship of Entities

Entity is the basic block for building the data collected about person, place, event, or thing.

* Entities represent attributes that can have multiple instances.

* Relationship denotes the link between the entities.

* Relationship between entities is represented through three relationships such as:

* 1:1 (one to one)

* 1:N (one to many)

* M:N (many to many)

a. STUDENT and COURSE (students register for courses)

* STUDENT and COURSE are two entities.

* Diagram representation of the relationship between entities:

COURSE

COURSE

STUDENT

STUDENT

M:N

* Student can study many courses and a course may contain many students.

* So, there is a many-to-many relationship between the entities.

b. BOOK and BOOK COPY (books have copies)

* BOOK and BOOK COPY are two entities

* Diagram representation of the relationship between entities:

BOOK COPY

BOOK COPY

BOOK

BOOK

1:M

* Book can have many copies, but book copy contains of one book only.

* So, there is a one-to-many relationship between the entities.

c. COURSE and SECTION (courses have sections)

* COURSE and SECTION are two entities

* Diagram representation of the relationship between entities:

SECTION

SECTION

COURSE

COURSE

1:M

d. SECTION and ROOM (sections are scheduled in rooms)

* SECTION and ROOM are two entities.

* Diagram representation of...