Book Image

MongoDB Fundamentals

By : Amit Phaltankar, Juned Ahsan, Michael Harrison, Liviu Nedov
Book Image

MongoDB Fundamentals

By: Amit Phaltankar, Juned Ahsan, Michael Harrison, Liviu Nedov

Overview of this book

MongoDB is one of the most popular database technologies for handling large collections of data. This book will help MongoDB beginners develop the knowledge and skills to create databases and process data efficiently. Unlike other MongoDB books, MongoDB Fundamentals dives into cloud computing from the very start – showing you how to get started with Atlas in the first chapter. You will discover how to modify existing data, add new data into a database, and handle complex queries by creating aggregation pipelines. As you progress, you'll learn about the MongoDB replication architecture and configure a simple cluster. You will also get to grips with user authentication, as well as techniques for backing up and restoring data. Finally, you'll perform data visualization using MongoDB Charts. You will work on realistic projects that are presented as bitesize exercises and activities, allowing you to challenge yourself in an enjoyable and attainable way. Many of these mini-projects are based around a movie database case study, while the last chapter acts as a final project where you will use MongoDB to solve a real-world problem based on a bike-sharing app. By the end of this book, you'll have the skills and confidence to process large volumes of data and tackle your own projects using MongoDB.
Table of Contents (15 chapters)
Preface

Conditional Operators

Now that you have learned how to query MongoDB collections, as well as how to use projection to return only specific fields in the output, it is time to learn more advanced ways of querying. So far, you've tried to query the comments collection using the value of a field. However, there are more ways to query documents. MongoDB provides conditional operators that can be used to represent various conditions, such as equality, and whether a value is less than or greater than some specified value. In this section, we will explore these operators and learn how to use them in queries.

Equals ($eq)

In the preceding section, you saw examples of equality checking where the queries used a key-value pair. However, queries can also use a dedicated operator ($eq) to find documents with fields that match a given value. For example, the following queries find and return movies that have exactly 5 comments. Both queries have the same effect:

db.movies.find({&quot...