An entity relationship model (ER model) is a way of representing the entities
and the relationships between the entities in order to create a database.
Element/Notation of ER model/diagram:
- Entity:
- Think of an entity as something in the real world that you can identify, like a person, place, or thing.
- It’s a specific object that exists and is different from other objects.
- Entities can be concrete (like a person) or abstract (like an idea).
- Entity Set:
- An entity set is just a collection or group of similar entities.
- For example, if “Person” is an entity, then the set of all people would be the “Person” entity set.
- Attribute:
- Attributes are the characteristics or properties that describe an entity.
- If “Person” is an entity, then attributes could include things like “Name,” “Age,” or “Address.”
- Attributes are like the details or features of an entity.
- Relationship:
- Relationships show how entities are connected or associated with each other.
- Picture a relationship as a link between entities.
- For instance, if “Person” is an entity and “Works for” is a relationship, it could connect a person to a company entity.