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Learn MongoDB 4.x

You're reading from   Learn MongoDB 4.x A guide to understanding MongoDB development and administration for NoSQL developers

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Product type Paperback
Published in Sep 2020
Publisher Packt
ISBN-13 9781789619386
Length 610 pages
Edition 1st Edition
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Author (1):
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Doug Bierer Doug Bierer
Author Profile Icon Doug Bierer
Doug Bierer
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Table of Contents (22) Chapters Close

Preface 1. Section 1: Essentials
2. Introducing MongoDB 4.x FREE CHAPTER 3. Setting Up MongoDB 4.x 4. Essential MongoDB Administration Techniques 5. Section 2: Building a Database-Driven Web Application
6. Fundamentals of Database Design 7. Mission-Critical MongoDB Database Tasks 8. Using AJAX and REST to Build a Database-Driven Website 9. Section 3: Digging Deeper
10. Advanced MongoDB Database Design 11. Using Documents with Embedded Lists and Objects 12. Handling Complex Queries in MongoDB 13. Section 4: Replication, Sharding, and Security in a Financial Environment
14. Working with Complex Documents Across Collections 15. Administering MongoDB Security 16. Developing in a Secured Environment 17. Deploying a Replica Set 18. Replica Set Runtime Management and Development 19. Deploying a Sharded Cluster 20. Sharded Cluster Management and Development 21. Other Books You May Enjoy

Querying a collection

The main command used to query a collection from the mongo shell is db.<collection_name>.find(). If you are only interested in a single result, you can alternatively use db.<collection_name>.findOne(). The find() and findOne() commands have two basic parameters: the query (also referred to as filter) and the projection, as illustrated in the following diagram:

The result of a query is a cursor. The cursor is an iteration, which means you need to type the it helper command in the mongo shell to see the remaining results. 

As mentioned here, the db.collection.find() shell method produces a cursor over which you can iterate to retrieve all results. There are a number of cursor methods that can be applied, which has the effect of modifying the final results. A number of examples in this section will demonstrate a few of the most important such methods. For more information, refer to https://docs.mongodb.com/manual/reference/method/js...
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