IT244 Introduction to Database

Introduction to Database

• The course is IT244, Introduction to Database, offered by the College of Computing and Informatics at Saudi Electronic University.
• The presentation's primary resource is "Fundamentals of Database Systems, Global Edition, 7th Edition (2017)" by Ramez Elmasri and Shamkant Navathe.

Databases and Database Users

• Databases are organized collections of related data with an inherent meaning. Random data is not a database.
• They represent some aspect of the real world (miniworld/universe of discourse).
• Database systems include the database itself and database management systems (DBMS) software, sometimes with application programs.
• A DBMS enables users to create, maintain, define, construct, manipulate, and share databases.
• A database catalog or dictionary stores meta-data.
• Databases have specific purposes and intended user groups.

Typical DBMS Functionality

• Defining databases includes specifying data types, structures, and constraints.
• Loading/constructing the database involves placing initial data into a secondary storage medium.
• Manipulating data includes retrieval (queries and reports), modification (insertions, deletions, and updates), and protection (security against malfunctions/ unauthorized access).
• Databases also facilitate processing and sharing among concurrent users and applications.
• Maintenance is important as databases evolve over time.

Main Characteristics of the Database Approach

• Self-describing: A DBMS catalog describes the database.
• Insulation between programs and data: Data model abstraction helps in changing data structures and storage methods without affecting programs.
• Support for Multiple Views: Each user can see a subset of the data pertinent to them.
• Sharing of Data and Multi-User Processing: Multiple users can access and update data concurrently.
• Concurrency Control: The system assures that each transaction is properly executed or aborted.
• Recovery: The DBMS records effects of completed transactions permanently.
• OLTP (Online Transaction Processing): Many concurrent transactions are possible in database applications (e.g., airline reservations, online banking).

Example of a Database (UNIVERSITY)

• Entities in a university database include students, instructors, departments, courses, and sections.
• Typical relationships include students taking sections/courses, courses having prerequisites, instructors teaching sections, and courses offered by departments.
• The presentation shows examples of tables describing the entities and relations, such as student records, course details, and section scheduling info.

Types of Database Users

• Database Administrators: Authorized and responsible for access controls, resource allocation, and security.
• Database Designers: Define the structure/constraints and communicate user needs.
• Casual End-Users: Periodically use the database, often through predefined applications.
• Naive End-Users: Access databases through ready-made applications (e.g., bank tellers, etc.).
• Sophisticated End-Users: Use more technical tools and applications connected with the database (e.g., analysts, engineers).
• Stand-alone End-Users: Manage their own personal databases.

Types of Database Applications

• Traditional Databases (applications in businesses)
• Multimedia Databases (containing multimedia elements like images, video, voice, etc.)
• Geographic Information Systems (GIS)
• Data Warehouses
• Real-time and active databases

Advantages of Using the Database Approach

• Controlling redundancy
• Restricting unauthorized access
• Improving query processing efficiency (e.g., indexes)
• Backup and recovery services
• Representing complex entity relationships.
• Integrity constraints
• Multiple user viewpoints
• Multiple views of same data

When Not to Use a DBMS

• Unnecessary Complexity: If the database and applications are simple and not expecting changes.
• Stringent Real-time Requirements: Database operations might have delays.
• Single-user applications: Access is not required by multiple users.
• Data complexity exceeding the DBMS capability.
• Performance limitations of the hardware/software components of the DBMS.

Historical Development of Database Technology

• Progressing from hierarchical, network, and inverted file systems to relational, object-oriented, object-relational, and now data on the web (e.g., e-commerce)
• XML is a data interchange standard.

Extensible Database Capabilities

• New functionality like scientific applications, XML, image/video management, data warehousing, spatial data, and time-series management.

Additional Implication and Considerations

• Enforcing standards within an organization.
• Reduced application development time.
• Data flexibility.
• The availability of up-to-date information.
• Scale economies and avoiding overlapping personnel and resources.