MongoDB : MongoDB Introduction

1. MongoDB Introduction

Definition

MongoDB is a popular NoSQL database that stores data in flexible, JSON-like documents. It provides high performance, high availability, and easy scalability. Documents in MongoDB can have different fields, and the structure can be changed over time.

Algorithm 1: Creating a Database :-

Step 1: Start MongoDB server

Step 2: Use the MongoDB shell command: use mydatabase

Step 3: Create a collection using: db.createCollection("mycollection")

Step 4: Verify database creation

Step 5: Stop

Example 1: Creating and Inserting Documents

// Insert a document

db.users.insertOne({

  name: "John Doe",

  age: 30,

  email: "john@example.com"

})

Algorithm 2: Querying Documents :-

Step 1: Connect to database

Step 2: Select collection using: db.collection

Step 3: Use find() method with query parameters

Step 4: Process results

Step 5: Close connection

Example 2: Querying Documents

// Find documents

db.users.find({

  age: { $gt: 25 },

  email: { $exists: true }

}).sort({ name: 1 })

Algorithm 3: Updating Documents :-

Step 1: Locate document to update

Step 2: Prepare update operation

Step 3: Use updateOne() or updateMany()

Step 4: Verify update success

Step 5: Handle any errors

Example 3: Updating Documents

                        // Update documents

                        db.users.updateMany(

                          { age: { $lt: 30 } },

                          { $set: { status: "young" } }

                        )