Week 2

Learning Outcomes / Objectives

By the end of this week, students should be able to:

1. Identify and describe the components of a database system.

2. Explain the functions of a DBMS.

3. Describe the three-schema (ANSI/SPARC) architecture.

4. Distinguish between physical and logical data independence.

5. Explain the roles of DBA, database designer, and end-users.

A complete database system consists of the following components:

Component	Description
Hardware	Physical computers, servers, storage disks, network infrastructure. E.g., the servers in a bank's data centre.
Software	The DBMS software itself (e.g., MySQL, Oracle), operating system, and application programs.
Data	The actual data stored (operational data) and the metadata (schema/catalogue describing the data).
Procedures	Rules and instructions for using and running the database (backup procedures, security policies).
People	Database Administrator (DBA), database designers, application developers, and end-users.

Functions of DBMS

A DBMS performs the following essential functions:

DBMS Function	Explanation
Data Definition	Allows users to define the database structure (schemas, tables, constraints) using a Data Definition Language (DDL).
Data Manipulation	Allows insertion, updating, deletion, and retrieval of data using a Data Manipulation Language (DML).
Data Security	Controls who can access what data. Implements authentication and authorisation.
Data Integrity	Enforces rules (constraints) to ensure data accuracy and consistency.
Concurrency Control	Manages simultaneous access by multiple users to prevent data corruption.
Backup and Recovery	Creates backups and restores the database to a consistent state after failures.
Data Dictionary Management	Maintains metadata (the catalogue) describing the structure of the database.
Transaction Management	Ensures that groups of operations either all succeed or all fail (atomicity).

Teaching and Learning Methods to be Employed