MongoDB mongosh Delete

Introduction

In MongoDB, deleting documents allows you to remove unwanted data from your collections. This tutorial will guide you through the various delete operations using mongosh.

Prerequisites

• MongoDB installed and running on your machine.

• Access to mongosh and a populated database with some documents to delete.

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

Step 2: Switch to the Database

Switch to the database where your collection is located.

1. Use a Database:

   use myNewDatabase

Step 3: Deleting Documents

1. Delete a Single Document

To delete a single document from a collection, use the deleteOne() method.

db.users.deleteOne({ name: "Pankaj" })

• This will delete the first document that matches the filter where the name is "Pankaj".

2. Delete Multiple Documents

To delete multiple documents that match the specified criteria, use the deleteMany() method.

db.users.deleteMany({ city: "Mumbai" })

• This will delete all documents where the city is "Mumbai".

3. Delete All Documents in a Collection

If you want to remove all documents from a collection but keep the collection itself, use deleteMany() with an empty filter.

db.users.deleteMany({})

• This will delete all documents in the users collection.

4. Deleting by ObjectId

If you want to delete a document using its unique _id, you can use the following command.

db.users.deleteOne({ _id: ObjectId("yourObjectIdHere") })

• Replace "yourObjectIdHere" with the actual ObjectId of the document you want to delete.

5. Verify Deletion

To verify that the deletion was successful, you can query the collection to check if the documents have been removed.

db.users.find()

• This will display all remaining documents in the users collection.

Conclusion

You have learned how to delete documents in MongoDB using mongosh. You can delete single or multiple documents, remove all documents in a collection, and delete by specific _id.

If you have any questions or need further guidance, feel free to ask!

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