deleteOne() — MongoDB Technical Interview Questions & Answers

Deletes the first document matching a filter.

deleteOne()

  • Simple meaning: deleteOne removes the first matching document.
  • How to use: db.students.deleteOne({ roll: 12 }).
  • Result: deletedCount 0 or 1.
  • Try this: insert, deleteOne, findOne — should be null.
  • Common mistake: deleteMany({ city: "Pune" }) when you meant one student.
  • Interview tip: First match only. Unique filter (roll/_id).

Technical Interview Tip: deleteOne with a unique field.

Code Examples for deleteOne()

deleteOne() — working example

db.users.deleteOne({ email: "ada@example.com" })

deleteOne() — deleteOne removes at most one matching document (the first match).

How to Explain deleteOne() to an Interviewer

How do you delete one student?

deleteOne({ roll: 12 })