Why updating documents matters in MongoDB - See It in Action

Why Updating Documents Matters in MongoDB

📖 Scenario: You are managing a small online bookstore database using MongoDB. You have a collection of books, and sometimes you need to update the information about a book, like its price or stock quantity, to keep the data accurate and useful for customers.

🎯 Goal: Learn how to update documents in a MongoDB collection to keep your data current and correct.

📋 What You'll Learn

Create a collection called books with three book documents

Add a variable to specify the book to update

Write an update query to change the price of the specified book

Add a final query to confirm the update was successful

💡 Why This Matters

🌍 Real World

Updating documents keeps your database accurate, which is important for online stores, inventory systems, and any app that changes data over time.

💼 Career

Database administrators and backend developers often update documents to reflect real-world changes, such as price changes, stock updates, or user information edits.

1

Create the books collection with initial documents

Create a books collection with these exact three documents: { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10, stock: 5 }, { title: "1984", author: "George Orwell", price: 15, stock: 8 }, and { title: "To Kill a Mockingbird", author: "Harper Lee", price: 12, stock: 7 }.

MongoDB

// Insert the three book documents into the books collection
// Your code here

Need a hint?

Use db.books.insertMany() with an array of objects to add multiple documents at once.

2

Specify the book to update

Create a variable called bookToUpdate and set it to { title: "1984" } to select the book you want to update.

MongoDB

db.books.insertMany([
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10, stock: 5 },
  { title: "1984", author: "George Orwell", price: 15, stock: 8 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 12, stock: 7 }
])

// Create a variable bookToUpdate to select the book with title "1984"
// Your code here

Need a hint?

Use const bookToUpdate = { title: "1984" } to create the variable.

3

Update the price of the selected book

Write an update query using db.books.updateOne() to change the price of the book selected by bookToUpdate to 18.

MongoDB

db.books.insertMany([
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10, stock: 5 },
  { title: "1984", author: "George Orwell", price: 15, stock: 8 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 12, stock: 7 }
])

const bookToUpdate = { title: "1984" }

// Update the price of the book "1984" to 18
// Your code here

Need a hint?

Use db.books.updateOne(bookToUpdate, { $set: { price: 18 } }) to update the price.

4

Confirm the update by finding the updated document

Write a query using db.books.findOne() with bookToUpdate to retrieve the updated book document.

MongoDB

db.books.insertMany([
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10, stock: 5 },
  { title: "1984", author: "George Orwell", price: 15, stock: 8 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 12, stock: 7 }
])

const bookToUpdate = { title: "1984" }

db.books.updateOne(bookToUpdate, { $set: { price: 18 } })

// Find the updated book document
// Your code here

Need a hint?

Use const updatedBook = db.books.findOne(bookToUpdate) to get the updated document.