Database Management Systems (DBMS)
Comprehensive Subject Summary & Core Concepts
Guide
Part 1: Introduction to Databases & Architecture
1. What is a Database & DBMS?
A database is an organized collection of structured
information, or data, typically stored electronically in a
computer system. A Database Management System
(DBMS) is the software that interacts with end-users,
applications, and the database itself to capture and
analyze data.
Purpose of DBMS:
It allows users to create, protect, read, update, and
delete data in a database efficiently without worrying
about how data is physically saved on the hard drive.
2. The Three-Schema Architecture
, The primary goal of database architecture is to separate
the user applications from the physical database. This is
achieved through the Three-Schema Architecture
(ANSI/SPARC model):
A. External Level (View Schema)
The highest level of abstraction. It describes only the
part of the database that is relevant to a specific user or
department (e.g., student portal showing only grades).
B. Conceptual Level (Logical Schema)
The middle level. It describes what data is stored in the
whole database and the relationships among that data
(e.g., tables, data types, and security constraints).
C. Internal Level (Physical Schema)
The lowest level of abstraction. It describes how the
data is actually stored on physical disks, including file
structures, record formats, and indexing.
Part 2: Relational Databases & Key Constraints
3. Relational Database Management Systems
(RDBMS)
Comprehensive Subject Summary & Core Concepts
Guide
Part 1: Introduction to Databases & Architecture
1. What is a Database & DBMS?
A database is an organized collection of structured
information, or data, typically stored electronically in a
computer system. A Database Management System
(DBMS) is the software that interacts with end-users,
applications, and the database itself to capture and
analyze data.
Purpose of DBMS:
It allows users to create, protect, read, update, and
delete data in a database efficiently without worrying
about how data is physically saved on the hard drive.
2. The Three-Schema Architecture
, The primary goal of database architecture is to separate
the user applications from the physical database. This is
achieved through the Three-Schema Architecture
(ANSI/SPARC model):
A. External Level (View Schema)
The highest level of abstraction. It describes only the
part of the database that is relevant to a specific user or
department (e.g., student portal showing only grades).
B. Conceptual Level (Logical Schema)
The middle level. It describes what data is stored in the
whole database and the relationships among that data
(e.g., tables, data types, and security constraints).
C. Internal Level (Physical Schema)
The lowest level of abstraction. It describes how the
data is actually stored on physical disks, including file
structures, record formats, and indexing.
Part 2: Relational Databases & Key Constraints
3. Relational Database Management Systems
(RDBMS)
