What are the primary constructs of an Entity-Relationship Diagram (ERD)?

The primary constructs of an Entity-Relationship Diagram (ERD) are entities, relationships, and attributes.

Entities represent real-world objects or concepts that have a distinct existence in the database, such as customers, products, or orders. Each entity is typically represented as a rectangle in an ERD.

Relationships illustrate how entities are related to one another, signifying the associations between them. They can represent various types of connections, such as one-to-one, one-to-many, or many-to-many relationships, and they are usually depicted as diamonds or lines connecting entities in the diagram.

Attributes provide additional details or characteristics about entities. These are properties that describe the entity, such as a customer's name, age, or address. In ERDs, attributes are commonly represented as ovals connected to their corresponding entities.

By focusing on these three constructs—entities, relationships, and attributes—an ERD facilitates the organization and representation of data in a structured manner, making it an essential tool for designing and understanding databases.