Lesson 4: Database Analysis and Design

A diagram that represents relationships among entities in a database..

Entity Relationship Diagram

3 Principal Components of ER Diagram

Entities

Attributes

Relationships

Represents the structure of the database with the help of a diagram.

Entity Relationship Model

A systematic process to design a database as it would require you to analyze all data requirements before implementing your database.

ER Modelling

He proposed ER Diagrams in 1971 to create a uniform convention that can be used as a conceptual modeling tool.

Peter Chan

He offered the data structure diagrams that also inspired his model.

Charles Bachman

Symbols Used in ER Diagrams:
It represents entity types

Rectangle

Symbol Used in ER Diagram:
Represents attributes

Ellipses

Symbol Used in ER Diagram:
Represents relationship types

Diamonds

Symbol Used in ER Diagram:
It links attributes to entity types and entity types with other relationship types

Lines

Symbol Used in ER Diagram:
It underlines the attributes

Primary Key

Symbol Used in ER Diagram:
Represents multi-valued attributes

Double Ellipses

Type of Entity

Weak Entity

Type of Attributes

Key Attribute

Composite Attribute

Multivalued Attribute

Derived Attribute

Type of Relationships

One-to-Many

One-to-One

Many-to-One

Many-to-Many