Entity Relationship Modeling

Contents 1 Example

Entity relationship modeling enables us to describe business information (data) and its inherent structure. ER models, also called an ER schema, are represented by ER diagrams.The entity relationship model is represented as a diagram, known as the entity relationship diagram (ERD). This diagram is used to show our understanding of data and is one of the components of the information architecture. This model is also used in later stages of business system design and development.

A note about terminology: An entity is any physical object, resource, concept, or incident (i.e., event) of relevance to the enterprise about which data can be kept. Each entity is an occurrence of an entity type. An Entity Type is the collection of all the entities to which a specific definition, common attribute type, a specific identifier and relationship type apply. Entity Types may be tangible, active, or conceptual. Examples of entity types may include:

• Customer
• Employee
• Supplier Examples of entities for these entity types may be:
• Bob Smith
• John Doe
• XYZ Shipping

Only Entity Types are graphically depicted on the entity relationship diagram.

Example