MongoDB is a document database. It stores data in a type of JSON format called BSON.

A MongoDB Document

Records in a MongoDB database are called documents, and the field values may include numbers, strings, booleans, arrays, or even nested documents.

Example Document

{
  "title": "Post Title 1",
  "body": "Body of post.",
  "category": "News",
  "likes": 1,
  "tags": ["news", "events"],
  "date": Date()
  }

Learning by Examples

Our "Show MongoDB" tool makes it easy to demonstrate MongoDB. It shows both the code and the result.

Example

Find all documents that have a category of "news".

db.posts.find( {category: "News"} )

SQL vs Document Databases

SQL databases are considered relational databases. They store related data in separate tables. When data is needed, it is queried from multiple tables to join the data back together.

MongoDB is a document database which is often referred to as a non-relational database. This does not mean that relational data cannot be stored in document databases. It means that relational data is stored differently. A better way to refer to it is as a non-tabular database.

MongoDB stores data in flexible documents. Instead of having multiple tables you can simply keep all of your related data together. This makes reading your data very fast.

You can still have multiple groups of data too. In MongoDB, instead of tables these are called collections.

Local vs Cloud Database

MongoDB can be installed locally, which will allow you to host your own MongoDB server on your hardware. This requires you to manage your server, upgrades, and any other maintenance.

You can download and use the MongoDB open source Community Server on your hardware for free.

To be able to experiment with the code examples, you will need access to a MongoDB database.

Sign up for a free MongoDB Atlas account to get started.

Creating a Cluster

After you have created your account, set up a free "Shared Cluster" then choose your preferred cloud provider and region.

By default, MongoDB Atlas is completely locked down and has no external access.

You will need to set up a user and add your IP address to the list of allowed IP addresses.

Under "Database Access", create a new user and keep track of the username and password.

Next, under "Network Access", add your current IP address to allow access from your computer.

Install MongoDB Shell (mongosh)

There are many ways to connect to your MongoDB database.

We will start by using the MongoDB Shell, mongosh.

Use the official instructions to install mongosh on your operating system.

To verify that it has been installed properly, open your terminal and type:

mongosh --version

You should see that the latest verion is installed.

The version used in this tutorial is v1.3.1.

Connect to the database

To connect to your database, you will need your database specific connection string.

In the MongoDB Atlas dashboard, under "Databases", click the "Connect" button for your Cluster.

Next, choose "Connect with the MongoDB Shell".

Copy your connection string.

Example

Your connection string should look similar to this:

mongosh "mongodb+srv://cluster0.ex4ht.mongodb.net/myFirstDatabase" --apiVersion 1 --username YOUR_USER_NAME

Paste your connection string into your terminal and press enter.

You will be prompted to enter your database user password that you created earlier.

You are now connected to the database!

What Next?

In the following sections we will use 'mongosh' to create, read, update, and delete (CRUD) items in your database.

After getting the basics down, we will move on to using MongoDB with other backend technologies like Node.js.

MongoDB: A NoSQL Database

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