Entity Relationship Diagrams (ERD)

Every Database should have an ER Diagram. These data models are tools used in analysis to describe the data requirements and assumptions in the system. They also set the stage for the design of databases.

There are three basic elements in ER models:

1. Entities are the "things" about which we seek information.
2. Attributes are the data we collect about the entities.
3. Relationships provide the structure needed to draw information from multiple entities.