What are CRUD operations in MongoDB?

// Insert one
db.users.insertOne({
  name: "John",
  email: "john@example.com",
  age: 30
});

// Insert many
db.users.insertMany([
  { name: "Alice", age: 25 },
  { name: "Bob", age: 35 }
]);

// Find all
db.users.find();

// Find with filter
db.users.find({ age: { $gt: 25 } });

// Find one
db.users.findOne({ email: "john@example.com" });

// Projection (select fields)
db.users.find({}, { name: 1, email: 1 });

// Update one
db.users.updateOne(
  { email: "john@example.com" },
  { $set: { age: 31 } }
);

// Update many
db.users.updateMany(
  { age: { $lt: 30 } },
  { $set: { status: "young" } }
);

// Replace entire document
db.users.replaceOne(
  { _id: ObjectId("...") },
  { name: "John Updated", age: 31 }
);

// Delete one
db.users.deleteOne({ email: "john@example.com" });

// Delete many
db.users.deleteMany({ status: "inactive" });