Database Management Systems (DBMS) Basics

What is a DBMS?

A Database Management System (DBMS) is software that allows users to create, retrieve, update, and manage data efficiently. It acts as an interface between the user and the database, ensuring data integrity, security, and consistency.

Why Use a DBMS?

Data Organization – Helps in structured storage and retrieval of data.
Concurrency Control – Multiple users can access data simultaneously.
Data Security – Provides authentication and authorization mechanisms.
Backup & Recovery – Ensures data safety in case of failures.

Types of DBMS

DBMS can be categorized into the following types:

1️⃣ Relational DBMS (RDBMS)

Uses tables (relations) to store data.
Examples: MySQL, PostgreSQL, SQL Server, Oracle.
Data is managed using Structured Query Language (SQL).

2️⃣ NoSQL DBMS

Stores unstructured and semi-structured data.
Examples: MongoDB, Firebase, Redis, Cassandra.
Ideal for big data and real-time applications.

3️⃣ Hierarchical DBMS

Organizes data in a tree-like structure.
Parent-child relationship between records.
Example: IBM Information Management System (IMS).

4️⃣ Network DBMS

Uses graph-like structures to store data.
More flexible than hierarchical DBMS.
Example: Integrated Database Management System (IDMS).

DBMS vs File System

Feature	DBMS	File System
Data Redundancy	Minimizes redundancy	High redundancy
Data Integrity	Enforced by constraints	No built-in integrity
Security	Access control, encryption	Limited security
Concurrency	Supports multiple users	No concurrency control
Backup	Automated backup & recovery	Manual backup

SQL Basics

Structured Query Language (SQL) is used to manage and manipulate databases.

Creating a Table

CREATE TABLE students (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  age INT,
  email VARCHAR(100) UNIQUE
);

Inserting Data

INSERT INTO students (id, name, age, email)
VALUES (1, 'John Doe', 22, 'john@example.com');

Retrieving Data

SELECT * FROM students WHERE age > 20;

Updating Data

UPDATE students SET age = 23 WHERE id = 1;

Deleting Data

DELETE FROM students WHERE id = 1;

Advantages of DBMS

✅ Efficient data storage and retrieval
✅ Data integrity and security
✅ Reduced data redundancy
✅ Supports multi-user environments

Conclusion

DBMS plays a crucial role in modern applications, ensuring efficient data management, integrity, and security. SQL remains the standard language for relational databases, while NoSQL is gaining popularity for large-scale applications.