Combining comparison operators in MongoDB - Mini Project: Build & Apply

Combining Comparison Operators in MongoDB Queries

📖 Scenario: You are managing a small online bookstore database. You want to find books that meet specific price and rating criteria to recommend to customers.

🎯 Goal: Build a MongoDB query that uses combined comparison operators to find books priced between $10 and $30 and with a rating greater than 4.

📋 What You'll Learn

Create a collection named books with sample book documents

Add a variable for the price range limits

Write a MongoDB query using $gte, $lte, and $gt operators combined with $and

Complete the query to find books matching the criteria

💡 Why This Matters

🌍 Real World

Filtering products or items in a database based on multiple conditions is common in online stores, inventory systems, and recommendation engines.

💼 Career

Understanding how to combine comparison operators in queries is essential for database querying roles, backend development, and data analysis.

1

Create the books collection with sample data

Create a variable called books and assign it a list of three book documents. Each document should have these exact fields and values: { title: "Book A", price: 15, rating: 4.5 }, { title: "Book B", price: 25, rating: 3.9 }, and { title: "Book C", price: 35, rating: 4.8 }.

MongoDB

# Create the books list with three book documents
# Your code here

Need a hint?

Use a list with three dictionaries, each representing a book with the exact fields and values.

2

Define the price range limits

Create two variables called min_price and max_price and set them to 10 and 30 respectively.

MongoDB

books = [
    { "title": "Book A", "price": 15, "rating": 4.5 },
    { "title": "Book B", "price": 25, "rating": 3.9 },
    { "title": "Book C", "price": 35, "rating": 4.8 }
]
# Define min_price and max_price variables
# Your code here

Need a hint?

Set min_price to 10 and max_price to 30 as numbers.

3

Write the MongoDB query with combined comparison operators

Create a variable called query and assign it a MongoDB query object that uses $and to combine these conditions: price greater than or equal to min_price, price less than or equal to max_price, and rating greater than 4. Use $gte, $lte, and $gt operators exactly as shown.

MongoDB

books = [
    { "title": "Book A", "price": 15, "rating": 4.5 },
    { "title": "Book B", "price": 25, "rating": 3.9 },
    { "title": "Book C", "price": 35, "rating": 4.8 }
]
min_price = 10
max_price = 30
# Create the query using $and with $gte, $lte, and $gt
# Your code here

Need a hint?

Use $and with a list of conditions combining $gte, $lte, and $gt for the fields.

4

Complete the query to find matching books

Create a variable called matching_books and assign it the result of filtering the books list using the query conditions. Use a list comprehension that checks each book's price and rating against the query criteria exactly as defined.

MongoDB

books = [
    { "title": "Book A", "price": 15, "rating": 4.5 },
    { "title": "Book B", "price": 25, "rating": 3.9 },
    { "title": "Book C", "price": 35, "rating": 4.8 }
]
min_price = 10
max_price = 30
query = {
    "$and": [
        { "price": { "$gte": min_price } },
        { "price": { "$lte": max_price } },
        { "rating": { "$gt": 4 } }
    ]
}
# Filter books using the query conditions
# Your code here

Need a hint?

Use a list comprehension to filter books matching all query conditions.