Object-Oriented Databases

Key Concepts

• Object-Oriented Data Model
• Inheritance
• Encapsulation
• Polymorphism

Object-Oriented Data Model

The Object-Oriented Data Model is a database model that stores data in the form of objects, similar to how data is represented in object-oriented programming languages. Each object contains both data and methods that operate on that data. This model is particularly useful for applications that need to model complex, real-world entities and their relationships.

Example: Consider a university system where students, courses, and professors are represented as objects. Each student object might have attributes like 'Name', 'ID', and 'CoursesEnrolled', along with methods to register for courses or view grades.

Inheritance

Inheritance is a key feature of object-oriented databases that allows objects to inherit properties and methods from other objects. This promotes code reuse and simplifies the representation of hierarchical relationships. For instance, a 'GraduateStudent' object can inherit attributes and methods from a 'Student' object, adding specific attributes like 'ThesisTopic'.

Example: In a vehicle management system, a 'Car' object can inherit from a 'Vehicle' object, which has attributes like 'Make', 'Model', and 'Year'. The 'Car' object can then add specific attributes like 'NumberOfDoors' and 'FuelType'.

Encapsulation

Encapsulation is the concept of bundling data and methods that operate on the data within a single unit, or object. This ensures that the data is only accessible through the methods provided, maintaining data integrity and security. For example, a 'BankAccount' object might encapsulate the account balance and provide methods to deposit and withdraw funds, ensuring that the balance is always accurate.

Example: In a healthcare system, a 'Patient' object might encapsulate personal information like 'Name', 'Address', and 'MedicalHistory'. Only authorized methods, such as 'UpdateMedicalHistory', can modify this data, ensuring privacy and data integrity.

Polymorphism

Polymorphism allows objects of different classes to be treated as objects of a common superclass. This enables flexibility and extensibility in the design of applications. For example, a method that processes 'Vehicle' objects can also process 'Car' and 'Truck' objects, as they both inherit from 'Vehicle'.

Example: In a game development system, a 'Character' object can have subclasses like 'Warrior', 'Mage', and 'Archer'. A method that handles character actions, such as 'Attack', can be polymorphic, allowing each subclass to implement its own version of the 'Attack' method, tailored to its specific abilities.