Lect 3 Object Oriented Model.pptx from m
- 1. Lecture III: Design ER data schema & Object Oriented Data Models • Design of ER Database schema, • Object-oriented data models; concepts, principles, • comparison with the relational model
- 2. Design of ER Database Schema • Designing an Entity-Relationship (ER) database schema is both an art and a science —it transforms real-world concepts into a structured data model that a database can understand. It's fantastic that you're eager to dive into programming and database design, especially with your creative mindset
- 3. ER Basic concepts an ER model represents data as entities, their attributes, and the relationships between them. Think of it as a blueprint for how data is structured and interconnected. Entities: Objects or concepts that are significant in the context—nouns like Student, Course, or Instructor. Attributes: Properties or details about an entity— adjectives or characteristics like StudentID, Name, or Date of Birth. Relationships: How entities are associated with one another—verbs like enrolls in or teaches.
- 4. Steps to Design an ER Database Schema Step 1: Identify Entities Step 2: Define Attributes for Each Entity Step 3: Establish Relationships Between Entities Step 4: Determine Cardinality and Participation Step 5: Resolve Many-to-Many Relationships Start by listing all the essential elements in your system Determine what information you need to store about each entity. Identify how entities interact with each other Cardinality specifies the number of instances in a relationship. One-to-One (1:1) One-to-Many (1:N) Many-to-Many (M:N) Many-to-many relationships are broken down using associative entities. Enrollment: StudentID (Foreign Key) CourseID (Foreign Key)
- 5. Drawing the ER Diagram Visual representation helps in understanding and communicating the design. Detailed Diagram with Attributes Entities and Relationships Diagram:
- 6. Implementing the Schema in a Database Once the ER diagram is completed, the next step is translating it into a database schema. • SQL Table Creation Examples:
- 7. Object Oriented Database Model An object data model is a data model based on object-oriented programming, associating methods (procedures) with objects that can benefit from class hierarchies. Thus, “objects” are levels of abstraction that include attributes and behavior. •An object-oriented data model is a data model that represents data and relationships in an object- oriented paradigm, integrating concepts from object- oriented programming into database design.
- 8. Object-based data models in database management systems (DBMS) focus on how data is represented, emphasizing entities and their interrelations. In these models, data and its relationships are encapsulated within structures called objects. This approach extends traditional entity-relationship (ER) models by incorporating concepts like encapsulation, object identity, and functions, allowing for a more complex and organized representation of data.
- 9. Definition of OODM in DBMS? • The OODM is a better representation of real- world challenges. Both the data and the relationship are contained into a single structure that’s known as an object in this model. • Developers can now store audios, pictures, videos, and other types of data in databases, which was previously impossible with the relational approach (Although you can store video and audio in relational DB, it is generally advised not to store them in the relational DB)
- 10. Need of Object Oriented Data Model • To represent the complex real world problems there was a need for a data model that is closely related to real world. • Object Oriented Data Model represents the real world problems easily. • In Object Oriented Data Model, data and their relationships are contained in a single structure which is referred as object in this data model. • In this, real world problems are represented as objects with different attributes. All objects have multiple relationships between them.
- 11. Basic Object Oriented data model
- 12. Core Concepts of Object-Oriented Data Models • Objects: are encapsulated entities that combine data (attributes) and behavior (methods). • Attributes are the properties of an object. • Methods are Functions or procedures associated with the object that define its behavior. • Metaphor: Think of an object like a Pokémon—it has attributes (type, abilities, stats) and behaviors (moves it can use). • Classes are Blueprints or templates from which objects are created. • Inheritance is Mechanism by which a subclass derives attributes and methods from a superclass.
- 13. Encapsulation refers to Bundling data and methods that operate on the data within one unit, and restricting access from outside interference. Polymorphism is the Ability of different objects to be accessed through the same interface, with each object responding differently. Object Identity (OID) Is A unique identifier assigned to each object, independent of its attribute values.
- 14. Understanding of OO MODEL • Objects – An object is an abstraction of a real world entity or we can say it is an instance of class. Objects encapsulates data and code into a single unit which provide data abstraction by hiding the implementation details from the user. For example: Instances of student, doctor, engineer in above figure.
- 15. Attribute An attribute describes the properties of object. For example: Object is STUDENT and its attribute are Roll no, Branch, Setmarks() in the Student class. Methods Method represents the behavior of an object. Basically, it represents the real-world action. For example: Finding a STUDENT marks in above figure as Setmarks(). Class A class is a collection of similar objects with shared structure i.e. attributes and behavior i.e. methods. An object is an instance of class. For example: Person, Student, Doctor, Engineer in above figure.
- 18. Applications of Object-Oriented Data Models • CAD/CAM Systems: Complex designs with interrelated components. • Multimedia Databases: Managing images, audio, and video as objects. • Geographic Information Systems (GIS): Representing spatial data and relationships. • Simulation and Modeling: Objects representing entities with behaviors.