Understanding Databases

Understanding databases in MongoDB

In MongoDB, a database is a physical container for collections. Each database contains its own set of files on the file system. A single MongoDB server can have multiple databases, and each database can have multiple collections.

Creating a Database

Databases are created implicitly when the first collection is created. However, you can switch to a database explicitly using the use command.

use myDatabase

Key Features of Databases

Some key features of databases in MongoDB include:

• Isolation: Each database is isolated from others, providing data segregation.
• Separate File Storage: Each database has its own set of files, allowing for independent management of storage.
• Multiple Databases: A single MongoDB server instance can support multiple databases, useful for multi-tenant applications.

Example: Creating and Using a Database

Below is an example of creating a database and adding collections to it:

// Switching to a new database
use companyDB

// Creating a collection
db.createCollection("employees")

// Inserting documents
db.employees.insertMany([
    { name: "Alice", age: 28, position: "Manager" },
    { name: "Bob", age: 24, position: "Engineer" },
    { name: "Charlie", age: 35, position: "CEO" }
])

// Querying the collection
db.employees.find({ position: "Engineer" })