Domain is where every attribute is defined by its corresponding set of values - Designing the System

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• Nirja Shah   -Posted on 15 Oct 15
  - The Entity-Relationship (ER) Model is based on the notion of real-world entities and relationships among them.
  
  - While creating a real-world scenario into the database model, the ER Model creates entity set, relationship set, general attributes and constraints.
  
  - We use the ER Model for the conceptual design of a database.
  
  Entity
  - It is a real world being, which has some properties called attributes.
  
  - Every attribute is defined by its corresponding set of values, called domain
  
  Relationship
  - The logical association among entities is called relationship.
  - Relationships are mapped with entities in various ways.
  - The number of association between two entities is known as mapping cardinalities
  
  - Different types of mapping cardinalities are:
  
  1. one to one
  2. one to many
  3. many to one
  4. many to many

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