ER model Flashcards
(10 cards)
What is a data model?
A graphical representation of data entities and their relationships.
What are the two main components of an ERM?
Entities and Relationships.
What is an entity?
A thing of interest to the business, such as a person, object, or concept.
What does a UID represent?
Unique Identifier for an entity.
What does a relationship document in an ER model?
Business rules and constraints between entities.
How do you resolve a Many-to-Many relationship?
By creating an associative entity.
What does cardinality define?
The number of instances that can be associated between entities (e.g., 1:1, 1:M, M:M).
What’s the difference between mandatory and optional relationships?
Mandatory must exist; optional may or may not.
What is the degree of a relationship?
The number of entities involved (e.g., Unary, Binary).
Who developed the ER model?
Peter Chen in 1976.
