updateOne() — MongoDB Technical Interview Questions & Answers

Updates the first document matching a filter.

updateOne()

  • Simple meaning: updateOne changes the first document that matches the filter.
  • How to use: db.students.updateOne({ roll: 12 }, { $set: { marks: 80 } }).
  • Try this: also $inc: { attempts: 1 } in the same update.
  • Common mistake: missing $set so the document is replaced. Or updateMany when you meant one.
  • Interview tip: Filter + update operators. matchedCount / modifiedCount in the result.

Technical Interview Tip: updateOne + $set. Say what happens without $set.

Code Examples for updateOne()

updateOne() — working example

db.users.updateOne(
  { email: "ada@example.com" },
  { $set: { role: "admin" } }
)

updateOne() — updateOne updates the first match; use update operators like $set / $inc.

How to Explain updateOne() to an Interviewer

How do you change Asha’s marks?

updateOne({ roll: 12 }, { $set: { marks: 80 } })