Find and Manipulate Data using Aggregation in MongoDB

Sort, Skip and Limit Records in MongoDB Aggregation

Write Joins in MongoDB

Group By and Sum in MongoDB

Perform Group Operations on Array Fields in MongoDB

MongoDB Aggregation Framework

Unlike the relational databases, MongoDB doesn't allow you to join collections using the simple `find` queries, but you can write the join queries using the aggregation framework. In this lesson, we learn how to join two collections to get the data in the format we want.

The aggregation operators that we cover in this video are:

- [`$lookup`](https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/index.html)
- [`$project`](https://docs.mongodb.com/manual/reference/operator/aggregation/project/index.html)
- [`$arrayElemAt`](https://docs.mongodb.com/manual/reference/operator/aggregation/arrayElemAt/index.html)

You can see the list of all the [available operators in the MongoDB docs.](https://docs.mongodb.com/manual/reference/operator/aggregation/)

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https://app.egghead.io/api/v1/lessons/mongodb-write-joins-in-mongodb/transcript

MongoDB Aggregation Framework

Write Joins in MongoDB

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