Delete with filter conditions in MongoDB - Mini Project: Build & Apply

Delete Documents with Filter Conditions in MongoDB

📖 Scenario: You manage a small online bookstore database. Over time, some books become outdated or discontinued. You want to clean up the database by deleting books that meet certain conditions.

🎯 Goal: Build a MongoDB query to delete documents from the books collection using filter conditions.

📋 What You'll Learn

Create a books collection with specific book documents

Add a filter condition variable to select books published before 2010

Write a delete query using the filter condition to remove old books

Confirm the delete query targets the correct documents

💡 Why This Matters

🌍 Real World

Cleaning up outdated or irrelevant data in a database to keep it accurate and efficient.

💼 Career

Database administrators and developers often need to delete records based on conditions to maintain data quality.

1

Create the books collection with sample documents

Create a variable called books and assign it an array with these exact documents: { title: 'Learn MongoDB', year: 2015 }, { title: 'Old Book', year: 2005 }, { title: 'Modern Database', year: 2020 }

MongoDB

const books = [
  // Your code here
];

Need a hint?

Use an array of objects with the exact titles and years given.

2

Create a filter condition for books published before 2010

Create a variable called filterCondition and set it to { year: { $lt: 2010 } } to select books published before 2010

MongoDB

const books = [
  { title: 'Learn MongoDB', year: 2015 },
  { title: 'Old Book', year: 2005 },
  { title: 'Modern Database', year: 2020 }
];

// Your code here

Need a hint?

Use MongoDB's $lt operator to filter years less than 2010.

3

Write the delete query using the filter condition

Write a line that calls db.books.deleteMany(filterCondition) to delete all books matching the filter condition

MongoDB

const books = [
  { title: 'Learn MongoDB', year: 2015 },
  { title: 'Old Book', year: 2005 },
  { title: 'Modern Database', year: 2020 }
];

const filterCondition = { year: { $lt: 2010 } };

// Your code here

Need a hint?

Use deleteMany with the filter condition variable.

4

Confirm the delete query targets the correct documents

Add a line that calls db.books.find() to check remaining documents after deletion

MongoDB

const books = [
  { title: 'Learn MongoDB', year: 2015 },
  { title: 'Old Book', year: 2005 },
  { title: 'Modern Database', year: 2020 }
];

const filterCondition = { year: { $lt: 2010 } };

db.books.deleteMany(filterCondition);

// Your code here

Need a hint?

Use find() to see which documents remain after deletion.