Update Operators
Use update operators to modify specific fields without replacing the entire document.
Example
// $set — set field values
db.users.updateOne(
{ name: "Alice" },
{ $set: { age: 29, city: "New York" } }
)
// $unset — remove a field
db.users.updateOne(
{ name: "Alice" },
{ $unset: { city: "" } }
)
// $inc — increment a number
db.products.updateOne(
{ name: "Laptop" },
{ $inc: { stock: -1 } } // decrease by 1
)
// $push — add to array
db.users.updateOne(
{ name: "Alice" },
{ $push: { hobbies: "gaming" } }
)Update Many & Replace
Update multiple documents at once or replace an entire document.
Example
// Update many documents
db.products.updateMany(
{ category: "Electronics" },
{ $set: { onSale: true } }
)
// Replace entire document
db.users.replaceOne(
{ name: "Bob" },
{ name: "Robert", email: "robert@example.com", age: 32 }
)
// Upsert — update or insert if not found
db.users.updateOne(
{ email: "new@example.com" },
{ $set: { name: "New User", age: 20 } },
{ upsert: true }
)