MongoDB - Overview

Hello, aspiring programmers! Today, we're going to embark on an exciting journey into the world of MongoDB. As your friendly neighborhood computer science teacher, I'm thrilled to guide you through this fascinating database system. Don't worry if you've never written a line of code before – we'll start from the very basics and work our way up. So, grab a cup of coffee (or your favorite beverage), and let's dive in!

What is MongoDB?

Before we get into the nitty-gritty details, let's understand what MongoDB is all about. MongoDB is a popular NoSQL database that provides high performance, high availability, and easy scalability. It's like a giant, super-organized filing cabinet for your data, but way cooler and more flexible!

A Brief History

MongoDB was created by the folks at 10gen (now MongoDB Inc.) in 2007. They were building a platform as a service (PaaS) product, but ended up focusing on the database component. The name "Mongo" comes from "humongous" because it can handle enormous amounts of data. Pretty clever, right?

Database

In MongoDB, a database is like a container that holds collections of data. Think of it as a big box where you keep all your related stuff together. For example, if you're building a library management system, you might have a database called "library".

Creating a Database

To create a database in MongoDB, you use the use command. Here's an example:

use library

This command creates a new database called "library" if it doesn't exist, or switches to it if it does. Easy peasy!

Collection

A collection in MongoDB is similar to a table in relational databases. It's a group of MongoDB documents. Continuing our library example, we might have collections for "books", "authors", and "members".

Creating a Collection

Creating a collection is super simple. Here's how you do it:

db.createCollection("books")

This creates a new collection called "books" in our "library" database. Cool, right?

Document

Now, we're getting to the heart of MongoDB. A document is a set of key-value pairs, similar to JSON objects. It's the basic unit of data in MongoDB. Each document in a collection can have a different structure – that's what makes MongoDB so flexible!

Sample Document

Let's look at a sample document for our "books" collection:

{
   "_id": ObjectId("5f5b7f2c3e8e9f1c9c8b4567"),
   "title": "To Kill a Mockingbird",
   "author": "Harper Lee",
   "published_date": ISODate("1960-07-11"),
   "pages": 281,
   "genres": ["Southern Gothic", "Bildungsroman"],
   "ratings": [
      { "user": "Alice", "score": 5 },
      { "user": "Bob", "score": 4 }
   ]
}

Let's break this down:

1. _id: This is a unique identifier automatically generated by MongoDB.
2. title, author, published_date, pages: These are simple key-value pairs.
3. genres: This is an array of strings.
4. ratings: This is an array of embedded documents.

The beauty of MongoDB is that you can have documents with different structures in the same collection. For instance, you could have another book document that includes additional fields like "edition" or "cover_type".

CRUD Operations

Now that we understand the basic structure, let's look at how we can manipulate our data. CRUD stands for Create, Read, Update, and Delete – the four basic operations you can perform on data.

Create (Insert)

To insert a document into a collection, you can use the insertOne() method:

db.books.insertOne({
   title: "1984",
   author: "George Orwell",
   published_date: new Date("1949-06-08"),
   pages: 328,
   genres: ["Dystopian", "Political fiction"]
})

This adds a new book to our "books" collection.

Read (Query)

To retrieve documents, we use the find() method. Here's how you can find all books by George Orwell:

db.books.find({ author: "George Orwell" })

Update

To update a document, we use the updateOne() method. Let's add a rating to our "1984" book:

db.books.updateOne(
   { title: "1984" },
   { $push: { ratings: { user: "Charlie", score: 5 } } }
)

This adds a new rating to the "ratings" array of the "1984" book.

Delete

To remove a document, we use the deleteOne() method:

db.books.deleteOne({ title: "1984" })

This removes the "1984" book from our collection.

Conclusion

Wow! We've covered a lot of ground today. We've learned about databases, collections, and documents in MongoDB, and even dipped our toes into some basic operations. Remember, practice makes perfect, so don't be afraid to experiment with these concepts.

MongoDB's flexibility and scalability make it a fantastic choice for many modern applications. As you continue your programming journey, you'll find that understanding MongoDB opens up a world of possibilities for handling and manipulating data.

Keep coding, stay curious, and remember – in the world of databases, you're the author of your own data story. Happy MongoDB-ing!

Operation	Method	Example
Create	insertOne()	db.books.insertOne({title: "1984", author: "George Orwell"})
Read	find()	db.books.find({author: "George Orwell"})
Update	updateOne()	db.books.updateOne({title: "1984"}, {$set: {pages: 328}})
Delete	deleteOne()	db.books.deleteOne({title: "1984"})

Credits: Image by storyset