C100DBA CRUD Operations Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  $remove

  Why it's wrong here

  $remove is not a valid update operator in MongoDB. Users often confuse it with the remove() method used for deleting entire documents. Attempting to use $remove in an update statement will cause a command error, as the server does not recognize this as a valid modification instruction.

• ✗

  $pop

  Why it's wrong here

  $pop only removes the first or last element of an array. It does not support removing specific elements based on their value or a matching condition. If you need to remove a specific item from the middle of an array, $pop is not the appropriate operator.

• ✓

  $pull

  Why this is correct

  $pull is the correct operator to remove all elements from an array that match a specific condition. It is efficient and atomic, allowing for precise modification of array fields without the need to read the full document state into the application, which is crucial for high-concurrency systems.

• ✗

  $unset

  Why it's wrong here

  $unset is used to remove an entire field from a document, not specific elements within an array. Using $unset on an array field would delete the entire array field from the document, which is likely not the desired behavior when only a single item needs to be removed.