Creating a Collection in MongoDB

Creating a Collection in MongoDB

Introduction

In MongoDB, collections are analogous to tables in relational databases. A collection is a grouping of MongoDB documents, and a database can contain multiple collections. This tutorial will guide you through the process of creating a collection using mongosh.

Prerequisites

• MongoDB installed and running on your machine.

• Access to mongosh. If MongoDB is installed correctly, you can access mongosh from the command line.

Step 1: Start mongosh

1. Open Terminal/Command Prompt:

   • Launch your terminal (macOS/Linux) or command prompt (Windows).

2. Start mongosh:

   • Type the following command and press Enter:

     mongosh

   • You should see a welcome message and the mongosh prompt:

     Current Mongosh Log ID: ...
     Connecting to: mongodb://localhost:27017

Step 2: Switch to the Database

Before creating a collection, you need to switch to the desired database. If you don’t have a specific database in mind, you can create a new one.

1. Use an Existing Database or Create a New One:

   • To switch to an existing database or create a new one (e.g., myNewDatabase), type:

     use myNewDatabase

   • You will see:

     switched to db myNewDatabase

Step 3: Create a Collection

You can create a collection in MongoDB by using the db.createCollection() method.

Creating a Collection

1. Create a Collection:

   • To create a collection named users, run the following command:

     db.createCollection("users")

   • You should see:

     { "ok" : 1 }

   • This indicates that the collection users has been successfully created.

Automatic Collection Creation

MongoDB also allows automatic collection creation when you insert the first document into a collection. For example:

1. Insert a Document to Create a Collection:

   • If you prefer to create a collection by inserting a document, use:

     db.products.insertOne({ productName: "Laptop", price: 50000 })

   • This command will create a collection named products if it does not already exist.

Step 4: Verify the Collection

1. Show Collections:

   • To check if the collections were created successfully, use:

     show collections

   • You should see users and products in the list of collections.

Step 5: Insert Documents into the Collection

Now that you have created a collection, you can insert documents into it.

1. Insert Multiple Documents:

   • To add multiple documents to the users collection, use the following command:

     db.users.insertMany([
       { name: "Pankaj", age: 30, city: "Indore" },
       { name: "Aditi", age: 25, city: "Mumbai" },
       { name: "Rahul", age: 28, city: "Delhi" }
     ])

2. Verify Inserted Documents:

   • To view the documents in the users collection, run:

     db.users.find()

   • You should see the documents you just inserted.

Step 6: Additional Operations

Dropping a Collection

If you want to delete a collection, you can do so with the drop() method.

1. Drop a Collection:

   db.users.drop()

   • This command will remove the users collection and all its documents.

Viewing Collection Statistics

You can also view statistics about a collection, such as the number of documents it contains.

1. Get Collection Stats:

   db.users.stats()

   • This command will return statistics about the users collection.

Conclusion

You have successfully created a collection in MongoDB using mongosh, both explicitly and implicitly by inserting documents. You also learned how to verify the collection, insert documents, and perform basic operations. In future tutorials, we will explore querying, updating, and deleting documents within collections.

Feel free to reach out with any questions or for further guidance!

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