Network Model && Hierarchical Model

Network Model
It uses pointers and links
Disadvantages of Network Model

• Design is not user friendly
• Doesn't have any scope of automated query optimization
• Fails in achieving structural independence even through the database model is capable of achieving data independence
• The schema or the structure of this database is very complex in nature as all the records are maintained by the use of pointers
• Complex and difficult to design and maintain
• Lacks standardization and portability Advantages - -This model avoids data duplications
• Support data security
• Flexibility -Efficient Querying -Data Independence
• Represents complex and many to many relationships efficiently -Multiple access path -Flexible data views

Hierarchical Model

• It is tree like structure
• One to many ( Single Parent to multiple children)
• Less Flexible
• Single access path
• Higher redundancy due to rigid hierarchy
• Simpler to design and implement
• Suitable for simple , hierarchical data structures
• Efficient for hierarchical traversal
• Real world occurrences of events are hierarchical in nature like biological structures , political or social structures

Example - Organizational Chart