Delete with filter conditions in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the deleteOne() method do in MongoDB?

It deletes the first document that matches the filter condition in a collection.

beginner

How do you delete multiple documents matching a condition in MongoDB?

Use the deleteMany() method with a filter to remove all documents that match the condition.

intermediate

What happens if you call deleteOne({}) with an empty filter?

It deletes the first document in the collection because the filter matches all documents.

beginner

Explain the filter condition in MongoDB delete operations.

The filter is a query object that specifies which documents to delete based on field values.

beginner

What is the difference between deleteOne() and deleteMany()?

deleteOne() removes only the first matching document, while deleteMany() removes all matching documents.

Which MongoDB method deletes all documents matching a filter?

A deleteMany()

B removeMany()

C removeOne()

D deleteOne()

deleteMany() deletes all documents that match the filter condition.

What does db.collection.deleteOne({ age: 30 }) do?

A Deletes documents where age is not 30

B Deletes all documents where age is 30

C Deletes the first document where age is 30

D Deletes the entire collection

It deletes only the first document matching the filter { age: 30 }.

If you want to delete documents where status is 'inactive', which filter is correct?

A { status: 'inactive' }

B { status: 'active' }

C { status: { $ne: 'inactive' } }

D {}

The filter { status: 'inactive' } matches documents with status equal to 'inactive'.

What happens if you call deleteMany({})?

A Deletes no documents

B Deletes all documents in the collection

C Deletes the first document only

D Throws an error

An empty filter matches all documents, so all are deleted.

Which method would you use to delete a single document by its unique _id?

A removeMany({ _id: id })

B deleteMany({ _id: id })

C remove({ _id: id })

D deleteOne({ _id: id })

deleteOne() is used to delete a single document matching the filter.

Describe how to delete documents in MongoDB using filter conditions.

Think about how you tell MongoDB which documents to remove.

What is the difference between deleteOne() and deleteMany() in MongoDB?

Focus on how many documents each method removes.