🗄️ Introduction to Database

Last Updated: 7th January 2026

A Database is an organized collection of data stored in a structured manner so that it can be easily accessed, managed, and updated.

Hinglish Tip 🗣: Database ka simple meaning hai — data ko ek safe aur systematic jagah par rakhna, jahan se hum data ko easily use kar sakein.

🤔 Why Do We Need a Database?

If data is stored only in simple files such as .txt or .csv, several problems arise:

  • Data duplication becomes common
  • Searching data is slow and inefficient
  • No proper security or access control
  • Multiple users cannot work reliably at the same time

👉 A database is designed to solve all these problems in a structured way.

📦 Real-Life Examples of Databases

  • Banking systems → customers, accounts, transactions
  • Educational institutions → students, marks, attendance
  • E-commerce platforms → products, orders, payments
  • Social media apps → users, posts, comments, likes

🧠 What Can We Do With a Database?

The basic operations performed on a database are called CRUD operations:

  • Create → insert new data
  • Read → retrieve existing data
  • Update → modify stored data
  • Delete → remove unwanted data

🗂️ Types of Databases

Database TypeDescriptionCommon Examples
Relational (SQL)Data stored in tables using rows and columnsMySQL, PostgreSQL, Oracle
Non-Relational (NoSQL)Flexible structure, not limited to tablesMongoDB, Redis
HierarchicalData organized in parent–child tree structureIBM IMS
NetworkSupports many-to-many relationshipsIDMS
Object-OrientedStores data as objects (classes & objects)ObjectDB

Relational Database Management System (RDBMS)

  • Data is stored in tables
  • Tables consist of:
    • Rows → records
    • Columns → attributes
  • Uses SQL (Structured Query Language)
  • Dr. Edgar Codd created RDBMS.

Example:

  • Table: Students
    • RollNo | Name | Marks

Non-Relational Database (NoSQL)

  • No fixed table schema
  • Data can be stored as:
    • Documents (JSON)
    • Key–Value pairs
    • Graphs or columns

Example:

{
  "name": "Rahul",
  "skills": ["Python", "SQL", "Pandas"]
}
  • ✔ Highly scalable
  • ✔ Flexible data model
  • ✔ Commonly used in real-time and big-data applications

💡 Database vs DBMS

  • Database → the actual data
  • DBMS (Database Management System) → software used to create, manage, and control databases

Examples of DBMS:

  • MySQL
  • PostgreSQL
  • MongoDB
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