ABSTRACT
This chapter begins by describing a data modeling approach and then introduces entity relationship (ER) diagrams. The concept of entities, attributes, relationships, and keys are introduced. The first three steps in an ER design methodology are developed. Step 1 begins by building a one-entity diagram. Step 2 concentrates on using structured English to describe a database. Step 3, the last section in this chapter, discusses mapping the ER diagram to a relational
What Is a Data Modeling Schema? What Is an Entity Relationship (ER) Diagram? Defining the Database-Some Definitions: Entity, Relationship, Attribute A Beginning Methodology ER Design Methodology A First “Entity-Only” ER Diagram: An Entity with Attributes More about Attributes The Simple or Atomic Attribute The Composite Attribute The Multi-valued Attribute The Derived Attribute The Keys English Description of the Entity The Method Mapping the Entity Diagram to a Relational Database Chapter Summary Chapter 2 Exercises References Case Study
database. These concepts-the diagram, structured English, and mapping-will evolve together as the book progresses. At the end of the chapter we also begin a running case study, which will be continued at the ends of the subsequent chapters.
