THE RELATIONAL DATABASE MODEL: ADDITIONAL CONCEPTS - Fundamentals of Database Management Systems - page 137

CHAPTER 6

THE RELATIONAL DATABASE

MODEL: ADDITIONAL

CONCEPTS

C hapter 5 defined the basic terminology of relational database and then
demonstrated some fundamental ideas about constructing relations in relational
databases and manipulating data in them. The discussion focused on relationships between
two different entity types, i.e. binary relationships. This chapter will go beyond binary
relationships into unary and ternary relationships. It will then address the important issue
of referential integrity.

OBJECTIVES

Describe how unary and ternary relationships are implemented in a relational
database.

■

Explain the concept of referential integrity. ■

Describe how the referential integrity restrict, cascade, and set-to-null delete rules
operate in a relational database.

■

CHAPTER OUTLINE
Introduction
Relational Structures for Unary and
Ternary Relationships
Unary One-to-Many Relationships
Unary Many-to-Many Relationships

Ternary Relationships
Referential Integrity
The Referential Integrity Concept
Three Delete Rules
Summary