To start the MongoDB Shell, open your terminal and type: mongosh.

You can connect to a specific database using the use command. If the database doesn’t exist, MongoDB will create it when you insert data.

use mydatabase

#Basic Commands

show dbs: Displays a list of all databases on the MongoDB server. show collections: Lists all collections in the currently selected database. db: Returns the name of the current database. db.<collection>: Switches to the specified collection in the current database. help: Provides help and documentation for MongoDB Shell commands.

#Creating a simple document and inserting it into a collection

use mydatabase db.mycollection.insertOne({ name: "John Doe", age: 30, city: "New York"})

#Querying documents

#Find all documents in a collection

db.mycollection.find()

#Find documents that match a specified condition

db.mycollection.find({ age: {$gt: 25 }})

The $gt operator is used here to find documents where the ‘age’ field is greater than 25. MongoDB supports a variety of query operators for different conditions.

#Updating Documents

db.mycollection.updateOne(
	{name: "John Doe"},
	{$set: { age: 31, city: "San Francisco" }}
);

We update the document with the name “John Doe”. The $set operator is used to set the ‘age’ to 31 and ‘city’ to “San Francisco”. If the document doesn’t exist, it won’t be updated.

#Updating Many

db.mycollection.updateMany(
	{ age: { $lt: 30 }},
	{ $set: { status: "Young Adult"}}
)

Update all documents where the ‘age’ is less than 30. The $set operator is used to add a new field ‘status’ with the value “Young Adult” to each matching document.

#Set Operator

Set a specific field in a document.

db.mycollection.updateOne(
	{name: "Alice"},
	{$set: {age: 25, city: "London"}}
)

#Inc Operator

Increment the value of a field in a document.

db.mycollection.updateOne(
	{name:"Bob"},
	{$inc: {age: 1}}
)

#Push Operator

Add an element to an array field in a document.

db.mycollection.updateOne(
	{ name: "Charlie"},
	{ $push: { hobbies: "Reading" }}
)

#Removing a Document

Delete a document db.mycollection.deleteOne({ name: "John Doe" })