$not operator behavior in MongoDB - Mini Project: Build & Apply

$not Operator Behavior in MongoDB Queries

📖 Scenario: You are managing a small online store's product database using MongoDB. You want to find products that do not match certain conditions, such as products that are not in a specific category or do not have a certain price range.

🎯 Goal: Build MongoDB queries using the $not operator to filter products that do not meet specific criteria.

📋 What You'll Learn

Create a collection named products with specific product documents.

Define a filter condition using $not to exclude products matching a condition.

Write a query that uses $not with a comparison operator inside.

Write a query that uses $not with a regular expression.

💡 Why This Matters

🌍 Real World

Filtering data in a database to exclude unwanted records is common in real-world applications like e-commerce, inventory management, and user data filtering.

💼 Career

Understanding how to use MongoDB query operators like <code>$not</code> is essential for backend developers, data engineers, and database administrators working with NoSQL databases.

1

Create the products collection with sample data

Create a MongoDB collection named products and insert these exact documents: { name: "Pen", category: "Stationery", price: 1.5 }, { name: "Notebook", category: "Stationery", price: 3 }, { name: "Coffee Mug", category: "Kitchenware", price: 7 }, { name: "Desk Lamp", category: "Electronics", price: 20 }, and { name: "Headphones", category: "Electronics", price: 50 }.

MongoDB

// Insert the specified documents into the products collection
// Your code here

Need a hint?

Use db.products.insertMany([...]) with the exact documents listed.

2

Define a filter to find products not in the Electronics category

Create a filter object named notElectronicsFilter that uses the $not operator to find products where the category is not equal to "Electronics".

MongoDB

db.products.insertMany([
  { name: "Pen", category: "Stationery", price: 1.5 },
  { name: "Notebook", category: "Stationery", price: 3 },
  { name: "Coffee Mug", category: "Kitchenware", price: 7 },
  { name: "Desk Lamp", category: "Electronics", price: 20 },
  { name: "Headphones", category: "Electronics", price: 50 }
])

// Define a filter named notElectronicsFilter using $not to exclude Electronics category
// Your code here

Need a hint?

Use { category: { $not: { $eq: "Electronics" } } } to exclude Electronics.

3

Write a query using $not to find products not priced above 10

Write a MongoDB query named notExpensiveProducts that finds products where the price is not greater than 10 using the $not operator with $gt.

MongoDB

db.products.insertMany([
  { name: "Pen", category: "Stationery", price: 1.5 },
  { name: "Notebook", category: "Stationery", price: 3 },
  { name: "Coffee Mug", category: "Kitchenware", price: 7 },
  { name: "Desk Lamp", category: "Electronics", price: 20 },
  { name: "Headphones", category: "Electronics", price: 50 }
])

const notElectronicsFilter = { category: { $not: { $eq: "Electronics" } } }

// Write a query named notExpensiveProducts to find products with price not greater than 10
// Your code here

Need a hint?

Use { price: { $not: { $gt: 10 } } } inside db.products.find().

4

Use $not with a regular expression to exclude products with names starting with 'D'

Write a query named notStartingWithD that finds products whose name does not start with the letter D using $not with a regular expression /^D/.

MongoDB

db.products.insertMany([
  { name: "Pen", category: "Stationery", price: 1.5 },
  { name: "Notebook", category: "Stationery", price: 3 },
  { name: "Coffee Mug", category: "Kitchenware", price: 7 },
  { name: "Desk Lamp", category: "Electronics", price: 20 },
  { name: "Headphones", category: "Electronics", price: 50 }
])

const notElectronicsFilter = { category: { $not: { $eq: "Electronics" } } }

const notExpensiveProducts = db.products.find({ price: { $not: { $gt: 10 } } })

// Write a query named notStartingWithD to find products whose name does NOT start with 'D'
// Your code here

Need a hint?

Use { name: { $not: /^D/ } } inside db.products.find().