Entity Relationship Diagram (ERD) Tutorial – Part 1

Learn how to create an Entity Relationship Diagram in this tutorial. We provide a basic overview of ERDs and then gives step-by-step training on how to make an ER diagram with correct cardinality.

Note: This tutorial promotes the tool ‘LucidChart’ – you do not have to use this tool specifically, unless it is your preference. Some alternatives to LucidChart are: Draw.io or DBDiagram.io.

Entity Relationship Diagrams are comprised of 3 main categories: entities, attributes, and relationships. Entities are objects or concepts that are associated with important data—like a customer, order, or product. Attributes represent properties or traits of an entity, such as a customer’s phone number or home address. Relationships demonstrate the link between entities.

Another main aspect of of ERD’s is cardinality, which further defines the relationship between entities in a numerical way. Certain symbols signify the minimum and maximum relationship between different entities.

Additional ERD information:

https://www.lucidchart.com/pages/how-to-draw-ERD

TIPS:

Identify the components

Entity-relationship diagrams are incredibly useful, and you can easily create one of your own by following these simple steps.

1. Determine the entities: Entities are typically nouns such as car, bank, student, or product.

In an ER Diagram, entities are the most important parts. To proceed, we will be creating a conceptual ER diagram of a simple system in which a student registers for a course that is taught by a professor. Check out this awesome tutorials to review ER Diagram Shapes. In this example, the three entities are “Student,” “Course,” and “Professor.”

2. Identify the relationships: Relationships highlight how entities interact with each other.

Relationships are typically verbs such as “buys,” “contains,” or “does.” In our example, the relationships “Registers for” and “Teaches” effectively explain the interactions between the three entities.

3. Add attributes: Attributes show specific characteristics of an entity, refining what information is important to the model.

In an ER Diagram, attributes are necessary to model what characteristics will be included with each entity. Attributes such as “IDNumber,” “Name,” and “SKU” are common attributes.

4. Complete the diagram

Organizing the ERD in a logical way is incredibly important to increase comprehension. The main purpose of entity-relationship diagrams is to model a complex database, so learning how to create simple, logical ERDs is key.