CRUD Operations

CRUD stands for Create, Read, Update, and Delete. These are the four basic functions of persistent storage.

1. CREATE (Insert)

Use `insertOne()` for a single document and `insertMany()` for multiple.

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

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

2. READ (Find)

Use `find()` to query documents. You can pass a filter object to refine results.

// Find All
db.users.find()

// Find with Filter
db.users.find({ name: "John Doe" })

// Find One (Returns the first matching document)
db.users.findOne({ age: { $gt: 25 } })

3. UPDATE

Use `updateOne()`, `updateMany()`, or `replaceOne()`. Always use the `$set` operator to update specific fields.

// Update One
db.users.updateOne(
  { name: "John Doe" }, // filter
  { $set: { age: 31 } } // update
)

// Update Many
db.users.updateMany(
  { age: { $lt: 30 } },
  { $set: { status: "active" } }
)

4. DELETE

Use `deleteOne()` or `deleteMany()` to remove documents from a collection.

// Delete One
db.users.deleteOne({ name: "John Doe" })

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

// Delete All Documents (Use with caution!)
db.users.deleteMany({})