Database model

• Database model

  A set of rules and standards that define how the database organizes data. It also defines how users view the organization of data.
• Types of Database Models

  • Hierarchical Model
  • Network Model
  • Relational Model
• Hierarchical Model

  • Arranges records in hierarchy like an organizational chart
  • Each record type is called a node or segment
  • A node represents a particular entity
  • The top-most node is called root
  • Each node is a subordinate of the node that is at the next higher level
  • A higher level node is called parent and lower level node is called child
  • A parent node can have one or many child nodes
  • A child node can have only one parent node
  • This kind of structure is often called inverted tree
• Network Model

  • Similar to hierarchical model
  • The difference is that child node can have more than one parent nodes
  • The child nodes are represented by arrows
  • It requires more complex diagram to represent a database
  • It provides more flexibility than hierarchical model
• Relational Model

  • The most commonly used database model
  • More flexible than hierarchical and network database models
  • Consists of simple relations
  • A relation is a term used for table
  • A relation represents a particular entity
  • It is used to store information about the entity
  • The relationships are based on the data of the entities