What is Entity Relationship Diagram (ERD)?

What is ERD?

An Entity-Relationship Diagram (ERD) is a graphical representation of a database that depicts the relationship between entities and the attributes of those entities (Elmasri & Navathe, 2016). Entities are objects or concepts that exist in the real world and are represented in the database, such as a customer or a product. Relationships are the connections between entities, such as a customer purchasing a product (Pratt & Adamski, 2018). Cardinalities are used to indicate the number of times an entity can be related to another entity, such as one-to-one or one-to-many (Halpin & Morgan, 2010). Attributes are characteristics that describe an entity, such as the name or age of a customer (Teorey, Lightstone, & Nadeau, 2011). ERDs are commonly used in database design to help visualize the structure of the database and ensure that all necessary information is included. They can also be used to identify potential issues or errors in the design (Elmasri & Navathe, 2016).

Some examples of ERD-related terms include:

Entity: an object or concept represented in the database

Relationship: a connection between entities

Cardinality: the number of times an entity can be related to another entity

Attribute: a characteristic that describes an entity


References

Elmasri, R., & Navathe, S. B. (2016). Fundamentals of database systems. Pearson.

Halpin, T., & Morgan, T. (2010). Information modeling and relational databases. Morgan Kaufmann.

Pratt, P. J., & Adamski, J. J. (2018). Concepts of database management. Cengage Learning.

Teorey, T. J., Lightstone, S. S., & Nadeau, T. (2011). Database modeling and design: logical design. Elsevier.

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