MongoDB CRUD Operations Flashcards

Which method is used to insert a single document into a MongoDB collection?

Answer: insertOne()

insertOne() inserts a single document into a collection and returns an acknowledgment with the inserted document's _id.

What does the findOne() method return when no matching document is found?

Answer: null

findOne() returns null when no document matches the specified query filter.

Which update operator sets the value of a field in a document?

Answer: $set

$set assigns a new value to the specified field, creating it if it does not already exist.

What option must be passed to updateOne() to create a new document if no match is found?

Answer: { upsert: true }

Setting upsert: true causes MongoDB to insert a new document when no document matches the filter criteria.

Which method removes a single document that matches the filter from a collection?

Answer: deleteOne()

deleteOne() deletes the first document that matches the filter, returning the count of deleted documents.

What does the $inc operator do in an update operation?

Answer: Increments or decrements a numeric field by a specified amount

$inc adds the specified value to a field's current value, and a negative value effectively decrements it.