DBMS Introduction Lecture 1

Introduction to DBMS and Data Modeling

• A database is an organized collection of information, facilitating easy access, management, and updates.
• Properties of a database include representing a real-world aspect (miniworld), being logically coherent, and serving specific user needs.
• Potential database issues: data size, ease of updating, accuracy, security, redundancy, and data importance.

Database Management System (DBMS)

• A DBMS is a software system for creating and managing databases, allowing users to manipulate data.
• Examples of DBMS applications include:
  • STUDENT file: Data on students.
  • COURSE file: Information on courses.
  • SECTION file: Details of course sections.
  • GRADE_REPORT file: Students' grades by section.
  • PREREQUISITE file: Information about prerequisite courses.

Characteristics of DBMS

• Provides security and reduces redundancy.
• Self-describing nature, allowing inherent meaning within the data.
• Insulates between programs and data for abstraction.
• Supports multiple views and shared data in multi-user environments.
• Follows ACID principles: Atomicity, Consistency, Isolation, Durability.

Types of Database Models

• Hierarchical Database
• Network Database
• Relational Database
• Object-Oriented Database

Hierarchical Database

• Data is structured in a tree-like format, maintaining parent-child relationships.
• Advantages:
  • Easy data retrieval due to explicit links.
  • Referential integrity is maintained automatically.
  • Conceptually simple and promotes data sharing.
• Disadvantages:
  • Difficult to add unrelated entries.
  • Does not support complex relationships or flexibility.

Network Database

• Allows each child to have multiple parents, improving flexibility over hierarchical models.
• Advantages:
  • Fast data access and supports complex queries.
• Disadvantages:
  • Requires detailed knowledge of database structure.
  • Updating is cumbersome and affects multiple application programs.

Relational Database (RDBMS)

• Organizes data into tables with unique keys identifying each row (records).
• Advantages:
  • Ease of use, network access, and language compatibility.
  • Prevents data redundancy and enhances data security.
• Disadvantages:
  • Higher costs and potential performance issues.
• Popular RDBMS examples include Oracle, SQL Server, MySQL, PostgreSQL, SQLite.

Object-Oriented Database (OOD)

• Interacts with complex data objects, similar to those in object-oriented programming.
• Key components include objects, attributes, methods, classes, and inheritance.
• Advantages:
  • Reusable generic objects and management of complex data types.
• Disadvantages:
  • Competition and complexity issues, lack of universal standards, and experience.

Entity-Relationship (ER) Diagram

• ER models are high-level conceptual data models representing entities and relationships.
• ER Diagrams (ERD) explain the logical structure of databases and assist in designing databases.
• Benefits of ER Diagrams include defining relationships, previewing table connections, and serving as blueprints for database implementation.

Components of ER Diagrams

• Entities: Real-world objects that can be recognized, such as persons, places, and events.
• Attributes: Properties of entities (e.g., a student entity may have attributes like name, age).
• Relationships:
  • One-to-many (1:M)
  • Many-to-many (M:N)
  • One-to-one (1:1)