The MongoDB local shell offers the capability to establish connections to both local and remote...

This comprehensive guide provides step-by-step instructions and practical examples to help you navigate MongoDB Shell and get started with basic commands.

Understanding Mongodb Shell Commands: A Comprehensive Guide

Getting Started With MongoDB Shell & Basic Commands

Below are a few MongoDB shell commands that you can begin familiarizing yourself with.

Install Mongosh on Mac using the command line.

Your default local port for Mongod will be 27017

To change the default port you can use the following command,

To check the local Database list, use the command below.

Finally, to select the database from the list, use the following command,

MongoDB shell commands

Moving on we can perform some basic operations on MongoDB shell.

To insert a single document, type the following command in MongoDB shell command terminal.

db.users.insertOne(
 {
   fullName: "The Favourite",
   email: [ "Drama", "History" ],
   subscription: 1
   isBlocked: false,
 }
)

To insert many documents at a single go, type the following command in MongoDB shell command terminal.

db.subscriptios.insertMany([
  {
   title: Basic,
   price: free,
   expire: 0,
   details: “”
  {
   title: glory,
   price: 10$,
   expire: 0,
   details: “”
  {
   title: premium,
   price: 50$,
   expire: 0,
   details: “”
  },
])

To update a single document, type the following command in MongoDB shell command terminal.

db.users.updateOne( { _id: "" },
{
 $set: {
   fullName: "Faraz Ahmed”
 }
})

To update many documents in a single go, type the following command in the MongoDB shell command terminal.

db.movies.updateMany(
 { price: { $lt: 50 } },
 {
   $set: { access: free, access_expire: 30 }
 }
)

To delete document, type the following command in MongoDB shell command terminal.

To delete documents many documents in a single go, type the following command in the MongoDB shell command terminal.

db.movies.deleteMany( { createdAt: { $ls: ""} } )

To find all the documents from the collection, type the following command in the MongoDB shell command terminal.

To get selective documents from the collection, type the following command in the MongoDB shell command terminal.

If you want to switch to another database temporarily, you can do it by running the following MongoDB shell commands.

db.getSiblingDB(<database name>).getCollectionNames();

MongoDB CRUD operation commands

db.movies.find( { genre: "Action", "rating": { $gte: 7 } } )

db.movies.find({
    year: 2010,
    $or: [ { "rating.wins": { $gte: 5 } }, { genres: "Drama" } ]
})

You can build a pipeline of queries/filtering to get specific data from the collection.

db.orders.aggregate( [


  // Stage 1: Filter pizza order documents by pizza size
  {
     $match: { size: "medium" }
  },
  // Stage 2: Group remaining documents by pizza name and calculate total quantity
  {
     $group: { _id: "$name", totalQuantity: { $sum: "$quantity" } }
  }

] )

On the first stage of the pipeline we will be filtering the data with a matching keyword where size is “medium”, then on the second stage we are grouping the filtered data with a “group” keyword.

Use of different conditional operators for queries like “and/or”

MongoDB utilizes indexes, which are data structures, designed to enhance query performance by facilitating efficient data retrieval from collections. Indexes store a condensed version of selected fields or values from the data, enabling the database to swiftly locate the desired documents. This optimization process significantly improves the efficiency of querying operations.

We can create multi keys indexes, text indexes, wildcard indexes and much more.

Indexes

Just like the join function in other databases like MySQL, you can also perform the join functionality in MongoDB.

Lookups

To join between collections we can use “lookup”.

{$lookup:
     {
        from: <joined collection>,
        let: { <var_1>: <expression>, …, <var_n>: <expression> },
        pipeline: [ <pipeline to run on joined collection> ],
        as: <output array field>
     }
}

{
    "title" : "my first post",
    "author" : "Jim",
    "likes" : 5
},
{
    "title" : "my second post",
    "author" : "Jim",
    "likes" : 2
},
{
    "title" : "hello world",
    "author" : "Joe",
    "likes" : 3
}

{
    "postTitle" : "my first post",
    "comment" : "great read",
    "likes" : 3
},
{
    "postTitle" : "my second post",
    "comment" : "good info",
    "likes" : 0
},
{
    "postTitle" : "my second post",
    "comment" : "i liked this post",
    "likes" : 12
},
{
    "postTitle" : "hello world",
    "comment" : "not my favorite",
    "likes" : 8
},
{
    "postTitle" : "my last post",
    "comment" : null,
    "likes" : 0
}

db.posts.aggregate([
    { $lookup:
        {
           from: "comments",
           localField: "title",
           foreignField: "postTitle",
           as: "comments"
        }
    }
])

You can also add a pipeline and run a multi-level query in a single aggregate.

Syntax

Connect local MongoDB to your local backend application.

Here we are connecting the local MongoDB to the node.js application, on which we will execute the above operations and more using the MongoDB shell.

const mongoose = require('mongoose');
const URI = mongodb://localhost:<local port number>/<database name>;
const connectDB = async () => {
    await mongoose.connect(URI, { useUnifiedTopology: true, useNewUrlParser: true })
    console.log("connected...!")
}
module.exports = connectDB;

After this, you can perform different operations in your local MongoDB database.

Local DB connectivity

As enterprise-level applications continue to evolve, MongoDB is increasingly recognized as a vital tool for data storage. If you are interested in getting started with MongoDB CLI, this article serves as a comprehensive guide to help you grasp the fundamentals of MongoDB.

Conclusion

The MongoDB local shell offers the capability to establish connections to both local and remote MongoDB servers. Once connected, you gain the ability to execute commands and scripts to effectively interact with the databases and collections residing within the MongoDB server.

The MongoDB local shell serves as an invaluable tool for developers and administrators involved in MongoDB operations. It enables the execution of JavaScript-based commands and offers a wide range of functionalities for managing databases, collections, documents, indexes, and other operations. With the local shell, you can seamlessly execute queries, update documents, perform data aggregation, create indexes, and handle administrative tasks efficiently.

MongoDB utilizes the BSON format for storing data, which is particularly advantageous and easily accessible within the realm of JavaScript

Let's start with some basic commands to access the database from the terminal.

Yes, it is possible to substitute SQL with MongoDB, but it's crucial to emphasize that the process of migrating from a SQL database to MongoDB demands meticulous thought and preparation. Since the data models and query languages vary, the transition may entail reevaluating the data structure, making adjustments to the application code, and adapting the queries to align with MongoDB's document model.

The ultimate decision to replace SQL with MongoDB hinges on your individual use case, technical requirements, and the compromises you are willing to accept.

Yes, MongoDB does provide support for joining data, although the approach is slightly different from traditional SQL joins. In MongoDB, we can utilize the $lookup operator to perform joins between two or more collections and retrieve the combined data.

Yes, MongoDB is well-suited for enterprise applications because of its extensive range of features that facilitate data security, flexible data storage, and various other essential capabilities. It provides a solid foundation for applications to scale and meet the demands of enterprise-level data management.

Moreover, MongoDB offers advanced functionalities such as replication and automatic sharding, which guarantee robustness and resilience for enterprise applications. It also includes a wide range of security features, including access controls, authentication mechanisms, and encryption choices, to safeguard critical enterprise data.

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Getting Started With MongoDB Shell & Basic Commands

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