ERD and its elements

ERD

"An Entity Relationship Diagram (ERD) is a type of diagram that lets you see how different entities (e.g. people, customers, or other objects) relate to each other in an application or a database" (Brumm, 2022).

Entity

An entity is an object about which data can be kept. It can be a physical thing (like a car or a person), a concept (like an address), or an occasion (e.g. student enrolment in a course). They stand in for nouns (Brumm, 2022).

Relationship 

In an ERD, a relationship describes the connections between two things. When referring to a database or a collection of entities, they might be derived from verbs (Brumm, 2022).

Typeso of relationship in ERD:

• One to one- one entity record is directly tied to another entity record.
• One to many- one entity record is tied to on eor more entity records.
• Many to many- many records tied to many records.

Attribute

"An attribute is a property of an entity or something that can be used to describe an entity" (Brumm, 2022).

Cardinalities

The term "cardinality" refers to how many instances of a given entity there are when there is a relationship between two entities (Brumm, 2022).

References

Brumm, B. (2022) Datastar. Available at: A Guide to the Entity Relationship Diagram (ERD) - Database Star  (Accessed: 14 March 2023).