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Major Data Model, DEGREES OF DATA ABSTRACTION - Coggle Diagram
Major Data Model
Hierarchical Model
Advantages:
Can form the foundation for current data models
Efficiency: When contain large number of relationships
Data integrity and security
Disadvantages :
Complex to implement
Difficult to manage
Lacks structural independence
Implementation limitations
Lack of standards
Relational Model
Advantages:
Tabular view improves
Ad hoc query capability is based on SQL
Structural independence is promoted
Isolates the end user from physical-level details
Improves implementation & management simplicity
Disadvantages :
Conceptual simplicity gives untrained people the tools to use a good system poorly
May promote information problems
Requires substantial hardware and system software overhead
Object-Oriented Model
Advantages:
Visual representation includes semantic content
Inheritance promotes data integrity
Semantic content is added
Disadvantages :
Compromised widely accepted standard
Complex navigational system
Slow development of standards caused vendors to supply their own enhancements
Learning curve is steep
High system overhead slows transactions
Network Model
Disadvantages :
system complexity limits efficiency
structural changes require changes in all application program
Advantages:
Handles more relationship
Conceptual simplicity
Conformance to standards
Data access is flexible
No SQL
Advantages:
Support big data
High scalability, availability and fault tolerance are provide
Uses low-cost commodity hardware
Disadvantages :
No relationship support
No transaction integrity support
Complex programming is required
DEGREES OF DATA ABSTRACTION
External
Requires that the modeler subdivide set of requirements & constraints into functional modules
ER diagrams are used to represent the external views
It is an end users' view of the data environment
Advantages:
• Easy to identified specific data
• Facilitates designer's job by providing feedback
• Helps to ensure security constraints in the database design
• Simplifies application program development
Conceptual
Most widely used conceptual model is the entity relationship (ER) model
Represents global view of the entire database
Provides a relatively easily understood macro level
Internal
Changing internal model without affecting the conceptual model
Representation of the database as "seen" by the Database Management System (DBMS)
Software dependent and hardware independent