Database Systems: Design, Implementation, and Management


Entity Relationship Database Model



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Database systems and benefits

Entity Relationship Database Model

  • Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel
  • Complements the relational data model concepts
  • Represented in an entity relationship diagram (ERD)
  • Based on entities, attributes, and relationships
  • Figure 1.13

Entity Relationship Database Model

  • Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel
  • Advantages
    • Exceptional conceptual simplicity
    • Visual representation
    • Effective communication tool
    • Integrated with the relational database model
  • Disadvantages
    • Limited constraint representation
    • Limited relationship representation
    • No data manipulation language
    • Loss of information content

Object-Oriented Database Model

  • Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel
  • Objects or abstractions of real-world entities are stored
    • Attributes describe properties
    • Collection of similar objects is a class
      • Methods represent real world actions of classes
      • Classes are organized in a class hierarchy
    • Inheritance is ability of object to inherit attributes and methods of classes above it

OO Data Model

  • Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel
  • Advantages
    • Adds semantic content
    • Visual presentation includes semantic content
    • Database integrity
    • Both structural and data independence
  • Disadvantages
    • Lack of OODM
    • Complex navigational data access
    • Steep learning curve
    • High system overhead slows transactions

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