The Entity-Relationship Model is a data model that helps us describe the organization of data for a particular scenario (business, or some other need). It was developed by Peter Chen and originally published in 1976. What we get is an abstract representation of the data by viewing the problem in terms of entities and relationships (that exist among the entities). Here are some good references for the ER Model:
- Conceptual Modeling Using the ER Model – Clear and concise; great set of notes.
- Wikipedia’s Entity-Relationship Model page
- Conceptual Design Using the ER Model (slides from a diff univ with the Ramakrishnan database book).
- Univ of Wyoming Lecture Notes for ER Model
- Chapter 5 of Churcher’s Beginning Database Design (more general, but still applicable). This book is available through SMU’s Central University Libraries website.
Some terms and concepts to pay attention to:
- Entity vs. Entity Set
- Relationship vs. Relationship Set
- Attribute
- Key, Primary Key, etc.
- Relationship Cardinalities (1:1, 1:M, M:N)
- Relationship Constraints (Total or Partial)
Different ER Model Notations:
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