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

 

(Freepik)

An ER Diagram, also known as an entity relationship diagram, is a flowchart that shows how "entities" link to one another inside a system. In software engineering, corporate information systems, education, and research, ER Diagrams are frequently used to build or troubleshoot relational databases (Dumitru, 2020).

Uses of entity relationship diagrams

Database design: An ERD, for instance, is frequently the first stage in identifying the requirements for an information systems project in software engineering. Later, it is employed to simulate a specific database or databases (Dumitru, 2020).

Database troubleshooting: To identify and fix issues with logic or deployment, ERDs are used to evaluate already-existing databases. Drawing the diagram should make it clear where things are going wrong (Dumitru, 2020).

Education: Planning databases that store relational information for educational reasons and subsequent retrieval can benefit from the use of ERDs (Dumitru, 2020).

Research: ERD diagrams can be crucial in creating effective databases for data analysis (Dumitru, 2020).

Components of ER Diagram

1. Entity

An item existing in the actual world that can be uniquely identified from other real-world things is referred to as an entity. Each entity possesses a set of characteristics or values for each of its qualities or attributes (Neha, 2021).

2. Attribute

In the database, each entity set is defined by a collection of attributes that specify the properties of each entity in that set (Neha, 2021). Other categories for the qualities include:

• Simple and Composite Attributes
• Single-valued and Multivalued Attributes
• Derived Attributes 

3. Relationship

Relationship explains how the entities that will be modelled are connected. For instance, the relationship between the teacher and the entity of the course is "teaches," meaning that the instructor teaches a certain course (Neha, 2021).

4. Mapping Cardinality

The amount of entities in one entity set that have relationships with entities in another entity set is known as mapping cardinality, sometimes known as the cardinality ratio (Neha, 2021).Assuming that there are two participating entity sets, A and B, the relationship between them can be:

• One-to-one
• One-to-many
• Many-to-one
• Many-to-many

Reference:

Dumitru, S. (2020) What is an entity relationship diagram (ERD)?, Medium. Medium. Available at: https://medium.com/@soni.dumitru/what-is-an-entity-relationship-diagram-erd-13daee5b2a (Accessed: March 8, 2023).

Freepik (no date) Free stock photos, royalty free stock images & Copyright Free Pictures ... Available at: https://www.pexels.com/ (Accessed: March 8, 2023).

Neha, T. (2021) What is entity relationship diagram (ERD)? uses, components, symbols & examples, Binary Terms. Available at: https://binaryterms.com/entity-relationship-diagram.html (Accessed: March 8, 2023).