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In software engineering, an Entity–Relationship model (ER) is a data model for describing the data or information aspects of a business domain or its process requirements, in an abstract way that lends itself to ultimately being implemented in a database such as a relational database. | Chapter 3 Data Modeling Using the Entity-Relationship ER Model ER Model Concepts ER Model Entity-relationship model describes data as entities attributes and relationships. Entities Entities are specific objects or things in the mini-world that are represented in the database. The basic object that the ER model represents is an entity - Example the EMPLOYEE John Smith. Attributes are properties used to describe an entity. Each entity has attributes. - Example an EMPLOYEE entity may have a Name Address Sex Birthdate. ER Model Concepts A specific entity will have a value for each of its attributes. - Example a specific employee entity may have Name John Smith Address 731 Fondren Houston TX Sex M BirthDate 09-JAN-55 Each attribute has a value set or data type associated with it - e.g. integer string enumerated type
