Getting Started

MongoDB Introduction

Learn MongoDB — the popular NoSQL database that stores data as flexible JSON documents.

What is MongoDB?

MongoDB is a document-oriented NoSQL database. Instead of storing data in rows and columns (like SQL), it stores data as documents — flexible, JSON-like structures.

SQL vs MongoDB Terminology

SQL	MongoDB
Database	Database
Table	Collection
Row	Document
Column	Field
JOIN	$lookup (aggregation)
Primary Key	_id

When to Use MongoDB

Good for:

Applications with evolving schemas
Hierarchical/nested data
High-volume, low-latency operations
Horizontal scaling needs

Not ideal for:

Complex transactions across many collections
Strong relational data with many JOINs
When data consistency is paramount

BSON

MongoDB stores data as BSON (Binary JSON), which extends JSON with additional types like ObjectId, Date, and BinData.

Example

javascript

// Documents look like JavaScript objects
{
  "_id": ObjectId("507f1f77bcf86cd799439011"),
  "name": "Alice Johnson",
  "email": "alice@example.com",
  "age": 30,
  "address": {
    "city": "Paris",
    "country": "France"
  },
  "hobbies": ["reading", "coding", "hiking"],
  "createdAt": ISODate("2024-01-15T10:30:00Z")
}

// MongoDB shell commands
// show dbs          -- list databases
// use myapp         -- switch to database
// show collections  -- list collections
// db.users.find()   -- query collection

// MongoDB Atlas (cloud) connection string
// mongodb+srv://username:password@cluster.mongodb.net/myapp

// Mongoose (Node.js ODM)
// npm install mongoose

Want to run this code interactively?

Try in Compiler