DATABASE THEORY – PREMIUM STUDY NOTES
1. Introduction
A database is an organized collection of related data, stored electronically. It allows efficient storage, retrieval, and management of
information. A Database Management System (DBMS) is software used to create, manage, and use databases.
2. Core Concepts
, A data model defines how data is organized. The most widely used is the relational model, where data is stored in tables.
A schema is the overall logical design of the database – the blueprint of tables, relationships, and constraints – without containing the
actual data.
An instance is the actual data stored in the database at a given time.
A table (relation) consists of rows (records) and columns (attributes).
3. Types of Data Models
Relational Model: Organizes data into tables. Uses set theory. Easily queried using SQL.
Hierarchical Model: Organizes data in a tree structure with parent-child relationships.
Network Model: Organizes data as a graph with many-to-many relationships.
1. Introduction
A database is an organized collection of related data, stored electronically. It allows efficient storage, retrieval, and management of
information. A Database Management System (DBMS) is software used to create, manage, and use databases.
2. Core Concepts
, A data model defines how data is organized. The most widely used is the relational model, where data is stored in tables.
A schema is the overall logical design of the database – the blueprint of tables, relationships, and constraints – without containing the
actual data.
An instance is the actual data stored in the database at a given time.
A table (relation) consists of rows (records) and columns (attributes).
3. Types of Data Models
Relational Model: Organizes data into tables. Uses set theory. Easily queried using SQL.
Hierarchical Model: Organizes data in a tree structure with parent-child relationships.
Network Model: Organizes data as a graph with many-to-many relationships.
