Creating Databases and Collections
MongoDB creates databases and collections automatically when you first insert data. You can also create them explicitly.
Example
// Switch to a database (creates if doesn't exist)
use shopDB
// Create collection explicitly
db.createCollection("products")
// Or just insert — collection is created automatically
db.products.insertOne({ name: "Laptop", price: 999 })
// List collections
show collections
// Drop a collection
db.products.drop()
// Drop entire database
db.dropDatabase()Collection Options
Collections can have options like capped size, validation rules, and more.
Example
// Capped collection (fixed size, FIFO)
db.createCollection("logs", {
capped: true,
size: 1048576, // 1MB max
max: 1000 // 1000 docs max
})
// Collection with validation
db.createCollection("users", {
validator: {
$jsonSchema: {
required: ["name", "email"],
properties: {
name: { bsonType: "string" },
email: { bsonType: "string" },
age: { bsonType: "int", minimum: 0 }
}
}
}
})