Fundamentals of Database Systems

Types of Databases and Applications

• Traditional Applications:
  • Numeric and Textual Databases
• Recent Applications:
  • Multimedia Databases
  • Geographic Information Systems (GIS)
  • Biological and Genome Databases
  • Data Warehouses
  • Mobile Databases
  • Real-time and Active Databases

Recent Developments

• Social Networks (e.g., Facebook, Twitter, LinkedIn) capture extensive data about people and their communications.
• Search Engines (e.g., Google, Bing, Yahoo) collect a repository of web pages for searching purposes.
• New technologies from non-database software vendors manage vast amounts of web-generated data:
  • Big Data Storage Systems involving large clusters of distributed computers.
  • NoSQL Systems designed for specific data processing needs.
  • Cloud Storage maintains massive data centers to house extensive datasets.

Basic Definitions

• Database: A collection of related data.
• Data: Known facts that can be recorded and have meaning.
• Mini-world: A subset of the real world represented in a database (e.g., student information).
• Database Management System (DBMS): Software/ system that facilitates the creation and maintenance of databases.
• Database System: The combination of DBMS software and the data itself, sometimes including applications.

Impact of Databases and Technology

• Businesses: Critical in banking, insurance, retail, transportation, healthcare, and manufacturing.
• Service Industries: Financial, real estate, legal, electronic commerce.
• Education: Provides resources for content delivery.
• Recent Fields: Increasing relevance in social networks, environmental applications, and personalized mobile apps.

Typical DBMS Functionality

• Define database concerning data types, structures, and constraints.
• Construct or load initial database contents on storage media.
• Manipulation:
  • Retrieval: Querying and generating reports.
  • Modification: Insertions, deletions, updates.
• Accessing the database through web applications.
• Ensuring data validity and consistency during multi-user access.

Application Activities Against a Database

• Queries: Accessing and formulating requests for specific data.
• Transactions: Operations that read and update the database.
• Ensuring Unauthorized access protection and adapting to changing user requirements.

Additional DBMS Functionality

• Protection measures against unauthorized access.
• Active processing (internal actions on data).
• Data presentation and visualization.
• Maintenance of the DBMS and underlying database.

Example of a University Database

Mini-World Components:

• Entities:
  • Students, Courses, Sections, Departments, Instructors.

Relationships:

• Sections belong to specific Courses.
• Students enroll in Sections.
• Courses may have prerequisites.
• Instructors teach Sections.

Characteristics of the Database Approach

• Self-describing Nature: Metadata stores descriptions of data (data structures, types, constraints).
• Program-Data Independence: Changes to data structures do not require modifications to application programs.
• Data Abstraction: Data models provide a conceptual view, hiding storage details.
• Multiple Views of Data: Different users can see tailored views aligned to their requirements.

Sharing Data and Transaction Processing

• Allows concurrent users to retrieve and update data.
• Concurrency Control: Ensures correctness during simultaneous operations.
• Recovery System: Ensures transactions are recorded permanently.
• Online Transaction Processing (OLTP): Supports numerous transactions per second.

Database Users

Types:

1. Actors on the Scene:

   • Database Administrators (DBA): Authorize access, monitor efficiency, manage resources.
   • Database Designers: Define structure and constraints, communicate user needs.
   • End-Users: Consume data for queries and reports.
     • Casual, Naïve/Parametric, Sophisticated, Stand-alone users.

2. Workers Behind the Scene:

   • System Analysts: Capture user requirements, design applications.
   • Tool Developers: Create supporting software and facilitate database management.
   • Operators: Maintain DBMS hardware and software environments.

Advantages of Database Approach

• Controls data redundancy.
• Facilitates data sharing among users.
• Protects against unauthorized access.
• Provides persistent storage, optimization of queries, and recovery services.
• Supports complex relationships and enforces integrity constraints.

Implications of Using Databases

• Establishes standards for data-related operations improving cohesiveness in production environments.
• Minimizes application development time and fosters flexibility in evolving data structures.
• Ensures access to current information, especially for real-time applications.

Historical Development of Database Technology

• Hierarchical and Network Models: Dominated in the 1960s and 70s.
• Relational Model: Introduced in 1970, revolutionizing data management.
• Object-oriented Database Management Systems (OODBMS): Emerged in the late 1980s addressing complex data applications.

Extending Database Capabilities

• New functionalities in scientific applications, XML data, image storage, and data warehousing.
• Social media and cloud-based storage are reshaping data management.
• The rise of Big Data technologies and NoSQL databases for massive dataset handling.

When Not to Use a DBMS

• High initial investment costs.
• Situations with simple data needs, single-user access, or stringent real-time requirements.
• Challenges in managing complex data with conventional DBMS models.