MongoDB CRUD Operations Flashcards

What does the replaceOne() method do differently from updateOne()?

Answer: It replaces the entire document except _id rather than updating specific fields

replaceOne() replaces the entire matching document with the new document, preserving only the _id field.

Which method inserts multiple documents into a collection in a single operation?

Answer: insertMany()

insertMany() accepts an array of documents and inserts all of them in one call, returning acknowledgment with all inserted _ids.

What is the purpose of the projection parameter in a find() query?

Answer: To specify which fields to include or exclude in results

Projection controls which fields appear in returned documents by specifying 1 to include or 0 to exclude specific fields.

Which query operator checks whether a field exists in a document?

Answer: $exists

$exists matches documents that have (or don't have) the specified field, depending on the boolean value provided.

What is the correct way to sort query results in descending order by a field named 'score'?

Answer: find().sort({ score: -1 })

Using -1 as the sort value specifies descending order, while 1 specifies ascending order.

What does the $pull operator do in MongoDB update operations?

Answer: Removes all array elements matching a condition

$pull removes from an array all elements that match a specified condition or value.