Welcome to MongoDB! MongoDB is a popular NoSQL database that stores data in flexible, JSON-like documents. Instead of tables and rows like in SQL, you have collections which contain documents. These documents are stored in a binary-encoded format called BSON (Binary JSON).

Let's dive into the four fundamental operations you'll perform on this data: Create, Read, Update, and Delete (CRUD).

Part 1: Using the Interactive Mongo Shell

The mongosh shell is a powerful command-line tool for interacting directly with your database. It's perfect for testing, debugging, and administrative tasks.

First, connect to your database by typing mongosh in your terminal.

Bash

# To switch to a database (it will be created if it doesn't exist)
> use myNewStore

# To see the current database
> db

Create: Inserting Documents

We use insertOne() to add a single document and insertMany() to add multiple.

JavaScript

// Insert a single product into the 'products' collection
> db.products.insertOne({ name: "Laptop", price: 1200, inStock: true })

// Insert multiple products at once
> db.products.insertMany([
    { name: "Mouse", price: 25, inStock: true },
    { name: "Keyboard", price: 75, inStock: false }
])

Read: Finding Documents

findOne() retrieves the first document that matches a query, while find() retrieves all matching documents as a cursor.

JavaScript

// Find a single product with the name "Laptop"
> db.products.findOne({ name: "Laptop" })

// Find all products that are in stock
> db.products.find({ inStock: true })

// You can add a second argument to find() for "projection" - to specify which fields to return
// Find all products, but only show their names (the _id is always returned by default)
> db.products.find({}, { name: 1, _id: 0 })

Update: Modifying Documents

Use updateOne() or updateMany(). You must use update operators (like $set, $inc) to specify the change.

JavaScript

// Update the price of the Laptop. The first document is the filter, the second is the update.
> db.products.updateOne(
    { name: "Laptop" },
    { $set: { price: 1150, lastModified: new Date() } }
)

// Increase the price of all products by 5
> db.products.updateMany(
    {}, // An empty filter matches all documents
    { $inc: { price: 5 } }
)

Delete: Removing Documents

Use deleteOne() or deleteMany() with a filter to specify which documents to remove.

JavaScript

// Delete the product named "Mouse"
> db.products.deleteOne({ name: "Mouse" })

// Delete all products that are not in stock
> db.products.deleteMany({ inStock: false })

Part 2: Using the Node.js Driver

In your application code, you'll use a driver to connect to and interact with MongoDB. Here’s how you perform the same CRUD operations in a Node.js script.

First, install the driver: npm install mongodb.

Code Snippet: crud.js

This script connects to a database, performs all four CRUD operations, and then closes the connection.

JavaScript

// crud.js
import { MongoClient } from 'mongodb';

// Connection URI
const uri = "mongodb://localhost:27017";
const client = new MongoClient(uri);

async function run() {
  try {
    // Connect to the server
    await client.connect();
    console.log("Connected successfully to MongoDB");
    
    const database = client.db("myNewStore");
    const products = database.collection("products");

    // --- CREATE ---
    const insertResult = await products.insertMany([
        { name: "Webcam", price: 60, tags: ["video", "usb"] },
        { name: "Monitor", price: 300, tags: ["display", "hdmi"] }
    ]);
    console.log(`Inserted ${insertResult.insertedCount} documents`);

    // --- READ ---
    const monitor = await products.findOne({ name: "Monitor" });
    console.log("Found one monitor:", monitor);

    // --- UPDATE ---
    const updateResult = await products.updateOne(
        { name: "Webcam" },
        { $set: { price: 55 } }
    );
    console.log(`Updated ${updateResult.modifiedCount} document`);

    // --- DELETE ---
    const deleteResult = await products.deleteOne({ name: "Webcam" });
    console.log(`Deleted ${deleteResult.deletedCount} document`);

  } finally {
    // Ensures that the client will close when you finish/error
    await client.close();
  }
}
run().catch(console.dir);