MongoDB Basics

  • What MongoDB is, differences between NoSQL and SQL databases, and MongoDB installation for backend development.

  • 🔹 What is MongoDB?

    MongoDB is a NoSQL, document-oriented database. Unlike traditional relational databases, MongoDB stores data in JSON-like documents (called BSON), making it flexible and scalable.

    Key Features:

    • Stores data as documents, not tables

    • Schema-less: each document can have different fields

    • High performance for read/write operations

    • Easy horizontal scaling

    Example Document in MongoDB:

Sample JSON Request Body

This JSON object represents a typical request body sent to an API. It includes user details such as name, email, age, and an array of skills, demonstrating how structured data can be sent from a client to a server for processing or storage. 

{
  "name": "Amit",
  "email": "amit@gmail.com",
  "age": 25,
  "skills": ["JavaScript", "Node.js", "MongoDB"]
}

  • 🔹 NoSQL vs SQL

    Databases can be categorized into SQL (Relational) and NoSQL (Non-relational). MongoDB falls into the NoSQL category.

    Feature

    SQL (MySQL, PostgreSQL)

    NoSQL (MongoDB)

    Structure

    Tables, Rows, Columns

    Collections, Documents

    Schema

    Fixed schema

    Flexible schema

    Query Language

    SQL

    MongoDB Query Language (MQL)

    Scaling

    Vertical scaling

    Horizontal scaling

    Best For

    Structured data

    Unstructured or semi-structured

    Example Comparison:

    SQL Table:

| id | name  | email          |
|----|-------|----------------|
| 1  | Amit  | amit@gmail.com |
  • MongoDB Document:

{
  "name": "Amit",
  "email": "amit@gmail.com"
}

  • 🔹 MongoDB Installation

    MongoDB can be installed locally or accessed via cloud (MongoDB Atlas). After installation, developers can manage databases using Mongo Shell, Compass GUI, or Mongoose (Node.js).

    Local Installation Steps

    1. Download MongoDB Community Server from the official website

    2. Install using default settings

    3. Start the MongoDB service (mongod)

    4. Verify installation:

mongo --version

  • MongoDB Atlas (Cloud)

    • Sign up at MongoDB Atlas

    • Create a free cluster

    • Connect your Node.js app using the connection string

    Example Node.js Connection:

MongoDB Atlas (Cloud) Setup & Node.js Connection

Set up a MongoDB Atlas cloud cluster and connect your Node.js app using Mongoose. This allows remote database access and management without a local MongoDB installation. 

const mongoose = require('mongoose');

mongoose.connect('mongodb+srv://<username>:<password>@cluster0.mongodb.net/myDB', {
  useNewUrlParser: true,
  useUnifiedTopology: true
})
.then(() => console.log('MongoDB connected'))
.catch(err => console.log(err));

  • MongoDB Compass (Local / GUI) Setup

    1. Open MongoDB Compass.

    2. Click “New Connection”.

    3. Enter connection string (ya localhost URL, e.g., mongodb://127.0.0.1:27017).

    4. Test connection → Connect.

    5. Once connected, create your database & collections via Compass GUI.

    Node.js Example (using Compass/Local MongoDB):

MongoDB Compass Setup & Node.js Connection

Set up MongoDB Compass to manage local databases and collections via GUI. Use Node.js with Mongoose to connect and perform database operations programmatically. 

const mongoose = require('mongoose');

mongoose.connect('mongodb://127.0.0.1:27017/myDB', {
  useNewUrlParser: true,
  useUnifiedTopology: true

})

.then(() => console.log('MongoDB connected via Compass/local'))

.catch(err => console.log(err));