Database & Information Systems – Full
High-Selling Premium Notes
1. What is a Database?
A database is a structured and organized collection of related information. Its purpose is to store,
manage, and retrieve data efficiently. Databases are used in schools, hospitals, banks, websites,
mobile apps, and almost every digital system. Key Features:
• Organized storage
• Fast searching
• Data safety
• Easy updating
2. What is DBMS?
A Database Management System (DBMS) is software that helps users create, store, modify, and
retrieve data from a database. It also ensures data security and reduces errors. Main Functions:
• Data storage management
• Data retrieval
• Backup & recovery
• Data sharing
• Security control
3. Types of Databases
a. Relational Database (Most common)
Stores data in tables (rows & columns).
Examples: MySQL, Oracle, SQL Server. b. NoSQL Database
Used for big unstructured data.
Examples: MongoDB, Firebase.
Stores data as objects (used in OOP).
Parent–child tree structure.
4. Core Concepts of DBMS
• Tables: Main structures storing data.
• Records (Rows): Individual data entries.
• Fields (Columns): Categories of data.
• Primary Key: Unique identity for each record.
• Foreign Key: Key linking two tables.
• Constraints: Rules to maintain data accuracy.
5. SQL (Structured Query Language)
SQL is the standard language for managing relational databases. Important Commands:
• SELECT – Fetch data
• INSERT – Add new record
• UPDATE – Modify existing data
• DELETE – Remove data
Example:
SELECT * FROM Students;
6. Normalization (Very important exam topic)
Normalization is the process of organizing data to reduce redundancy and improve data integrity.
Main Normal Forms:
• 1NF – Remove repeating groups
• 2NF – Partial dependency removed
• 3NF – Transitive dependency removed
High-Selling Premium Notes
1. What is a Database?
A database is a structured and organized collection of related information. Its purpose is to store,
manage, and retrieve data efficiently. Databases are used in schools, hospitals, banks, websites,
mobile apps, and almost every digital system. Key Features:
• Organized storage
• Fast searching
• Data safety
• Easy updating
2. What is DBMS?
A Database Management System (DBMS) is software that helps users create, store, modify, and
retrieve data from a database. It also ensures data security and reduces errors. Main Functions:
• Data storage management
• Data retrieval
• Backup & recovery
• Data sharing
• Security control
3. Types of Databases
a. Relational Database (Most common)
Stores data in tables (rows & columns).
Examples: MySQL, Oracle, SQL Server. b. NoSQL Database
Used for big unstructured data.
Examples: MongoDB, Firebase.
Stores data as objects (used in OOP).
Parent–child tree structure.
4. Core Concepts of DBMS
• Tables: Main structures storing data.
• Records (Rows): Individual data entries.
• Fields (Columns): Categories of data.
• Primary Key: Unique identity for each record.
• Foreign Key: Key linking two tables.
• Constraints: Rules to maintain data accuracy.
5. SQL (Structured Query Language)
SQL is the standard language for managing relational databases. Important Commands:
• SELECT – Fetch data
• INSERT – Add new record
• UPDATE – Modify existing data
• DELETE – Remove data
Example:
SELECT * FROM Students;
6. Normalization (Very important exam topic)
Normalization is the process of organizing data to reduce redundancy and improve data integrity.
Main Normal Forms:
• 1NF – Remove repeating groups
• 2NF – Partial dependency removed
• 3NF – Transitive dependency removed
