What is an ERD. Define the RED related terms, including entities, attributes, cardinalities and relationships



Entity-Relationship Diagram (ERD):

An ERD is a diagram that allows you to notice the entities and how they interconnect with each other. An ERD also has specific shapes, symbols, and arrows to describe the diagram. They are used to understand how a database system is going to be structured.

RED related terms:

-Entities: They are considered as objects that can store data about it. In other words, they represent nouns. Also, they are placed into a rectangular on the ERD. There are also weak entities and strong entities.

-Attributes: They are used to explain an entity. They can be described using an oval shape in an ERD. In addition, there are multiple types of attributes, such as simple, composite, and derived. Attributes can involve single values or multi values.

-Relationships: They explains how two entities are related to each other. They can be considered a verbs to explain the relationship better. Furthermore, there a types of relationships, such as one to one, one to many, and many to many.

-Cardinality: They portray the number of instances found in an entity between two entities in a relationship. They can also be expressed as a number or a symbol. Also, the cardinality value can be divided into zero, one, or many values.

Reference List:

Brumm, B. (2022) A Guide to the Entity Relationship Diagram (ERD). Available at: A Guide to the Entity Relationship Diagram (ERD) - Database Star (Accessed: 15 February 2023).

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