Introduction

In the previous chapters, we learned the fundamentals of interacting with MongoDB. With these basic operations (insert, update, and delete), we can now begin exploring and manipulating our data as we would with any other database. We also observed how, by fully leveraging the find command options, we can use operators to answer more specific questions about our data. We can also sort, limit, skip, and project on our query to create useful result sets.

In more straightforward situations, these result sets may be enough to answer your desired business question or satisfy a use case. However, more complex problems require more complex queries to answer. Solving such problems with just the find command would be highly challenging and would likely require multiple queries or some processing on the client side to organize or link the data.

The basic limitation is where you have data contained in two separate collections. To find the correct data, you would have to run...