Chapter 1

Chapter 1: Introduction to Databases

• Overview of databases and their importance in managing data effectively.

Objectives

• Common uses of database systems.

• Characteristics of file-based systems.

• Problems associated with file-based approaches.

• Definitions of key terms:

  • Database

  • Database Management System (DBMS)

Important Concepts

Typical Functions of a DBMS

• Data management and consistency.

• Support for data inquiries.

• Data security and integrity.

Major Components of the DBMS Environment

• Hardware: range from PCs to networks.

• Software: includes DBMS, operating systems, and application programs.

• Data: organization's data and schema descriptions.

• Procedures: rules for design and usage of the database.

• People: users and professionals involved in data management.

Personnel in the DBMS Environment

• Data Administrator (DA)

• Database Administrator (DBA)

• Database Designers (Logical and Physical)

• Application Programmers

• End Users (naive and sophisticated)

History of DBMS Development

• First-generation: Hierarchical and Network

• Second-generation: Relational

• Third-generation: Object-Relational and Object-Oriented

Applications of Databases

• Supermarket purchases.

• Credit card transactions.

• Holiday bookings.

• Local library lending.

• Insurance processing.

• Subscription payments for services.

• Public transport ticketing.

• Academic enrollment.

File-Based Systems

• Definition: A collection of application programs managing their own data independently.

• Issues associated with file-based systems:

  • Separation and isolation of data leading to unawareness of useful data.

  • Duplication increasing storage waste and inconsistency.

Limitations of File-Based Approach

• Data dependence: file structure embedded in code makes upgrades difficult.

• Incompatible file formats due to differing programming languages.

• Fixed Queries and proliferation of applications requiring unique solutions for each new requirement.

Database Approach

• Emerged to provide control over access and manipulation of data.

• Definition: A shared collection of logically related data designed to meet organizational information needs.

• Involves metadata for program-data independence and encompasses entities, attributes, and relationships.

Database Management System (DBMS)

• Software that enables users to define, create, maintain, and control database access.

• Allows interaction through application programs using SQL statements.

Database Definitions and Languages

Data Definition Language (DDL)

• Specifies data types, structures, and constraints; all specifications stored in the database.

Data Manipulation Language (DML)

• Provides a query language for data inquiries.

Controlled Access to Databases

• May include:

  • Security systems

  • Integrity systems

  • Concurrency control systems

  • Recovery control systems

  • User-accessible catalog

Views in Databases

• Allows users to have individual views of the database, representing subsets of data.

Benefits of Views

• Reduce complexity.

• Enhance security.

• Customize database appearance.

• Maintain consistency of database structure over changes.

Advantages of DBMSs

• Control of data redundancy leads to less duplicate data.

• Improved consistency and integrity of data.

• Enhanced sharing of data and improved security.

• Accommodates more information from the same amount of data.

• Economies of scale in data management.

• Improved data accessibility and responsiveness, increasing productivity.

• Facilitates effective backup and recovery services.

Disadvantages of DBMSs

• Complexity of systems may require specialized staff.

• Size and cost of DBMS implementation.

• Additional hardware needs for DBMS operation.

• Performance may be affected in larger systems, leading to potential data management challenges.