Introduction to Database Systems and Their Characteristics

Posted on Sep 9, 2024 in Computers

Information Systems and Databases

Life Cycle of an Information System

An organization’s information system comprises all resources used for collecting, managing, and utilizing information. The life cycle of an information system involves several stages:

  1. Feasibility Analysis: Analyzing potential application areas and conducting cost-benefit studies.
  2. Requirements Collection and Analysis: Gathering and analyzing user requirements.
  3. Design: Designing the system architecture and database schema.
  4. Implementation: Implementing the system, loading the database, and testing transactions.
  5. Validation and Acceptance Testing: Ensuring the system meets user requirements and performance criteria.
  6. Operation: Monitoring system performance and conducting maintenance.

What is a Database?

A database is a set of interrelated data with the following properties:

  • Represents a real-world aspect (e.g., a business or a process).
  • Is logically consistent and meaningful.
  • Is designed, built, and populated for a specific purpose.
  • Serves a specific user group with predefined applications.

A database can be defined as an integrated data repository with controlled redundancy. It reflects real-world relationships and constraints, allowing data sharing among different users and applications while remaining independent of them. Each data type has a unique definition and description, and common update and retrieval procedures ensure data integrity, security, and confidentiality.

Database Management System (DBMS)

A DBMS is a software package that enables users to create and maintain a database.

Desirable Characteristics of a DBMS:

  • Controlled Redundancy: Managing data redundancy to improve efficiency and consistency.
  • Restriction of Unauthorized Access: Implementing security measures to protect data from unauthorized access.
  • Data Inferences: Allowing the deduction of new information from stored data using rules.
  • Multiple User Interfaces: Providing different interfaces to cater to diverse user expertise levels.
  • Representation of Complex Links: Representing and efficiently managing complex data relationships.
  • Integrity Constraint Enforcement: Defining and enforcing rules to maintain data integrity.
  • Backup and Recovery: Providing mechanisms for data backup and recovery.

Users of a Database

Different types of users interact with a database:

  • Database Administrator: Manages database access, coordinates usage, and acquires necessary resources.
  • End Users: Access the database for querying, updating, and reporting. They can be categorized as:
    • Sporadic: Accessing occasionally with varying information needs.
    • Simple: Performing routine queries and updates.
    • Advanced: Utilizing DBMS resources for complex requirements (e.g., engineers, scientists).
    • Autonomous: Using databases embedded in commercial software with user-friendly interfaces.
  • Systems Analysts: Determine end-user requirements and develop specifications for transactions.

Characteristics of the Database Approach

Self-Descriptive Nature

A key characteristic of the database approach is that the system contains not only the database itself but also its complete definition or description. This information is stored in the system catalog, which includes details about file structures, data types, storage formats, and data constraints.

Separation of Programs and Data

Programs accessing the DBMS are written to be independent of specific files. The structure of data files is stored in the DBMS catalog, separate from the access programs. This property is called data independence.

Multiple Views of Data

A database typically serves multiple users, each requiring a different perspective or view of the data. The DBMS supports the creation and management of these different views.

Data Sharing and Multi-user Transaction Processing

The DBMS facilitates data sharing among multiple users and ensures data consistency through concurrency control mechanisms. These mechanisms manage simultaneous data updates to prevent conflicts and maintain data integrity.