updateMany() — MongoDB Technical Interview Questions & Answers

Updates every document matching a filter.

updateMany()

  • Simple meaning: updateMany applies the update to every matching document.
  • How to use: db.students.updateMany({ city: "Pune" }, { $set: { batch: "A" } }).
  • Try this: two Pune students, updateMany, find to verify both changed.
  • Common mistake: updateMany({}) in production — updates everyone. Always check the filter.
  • Interview tip: Many docs. Contrast updateOne. Empty filter is dangerous.

Technical Interview Tip: updateMany needs a careful filter.

Code Examples for updateMany()

updateMany() — working example

db.users.updateMany(
  { city: "Pune" },
  { $set: { active: true }, $inc: { loginCount: 1 } }
)

updateMany() — updateMany applies the update to every matching document.

How to Explain updateMany() to an Interviewer

updateOne vs updateMany?

First match vs every match