Overview

In this tutorial, we will discuss various ER-Diagram notations. These notations help visually represent the structure of the database under design. Different symbols denote entities, attributes, relationships, constraints, etc.

ER-Diagram Notations

ER-Diagram is a visual representation of data that describes how data is related to each other.

• Rectangle: The rectangle symbol represents entity types in the ER Diagram.
• Oval/ Ellipse: The oval symbol represents the attributes of the entity
• Diamond: The diamond symbol represents relationships in the diagram.
• Connecting Lines: Lines link attributes to entity types and entity types with other relationship types in the diagram.
• Primary key attributes are underlined in the diagram.
• Double ovals/ellipses: Represent multi-valued attributes.

 

Note that variations of these notations exist depending on the specific ER diagramming tool or methodology used.