Introduction to NoSQL & MongoDB

Workplace Context

Your team is building a new application that requires a flexible data model to handle large volumes of unstructured data. The development team has chosen MongoDB, a popular NoSQL database. As a developer, you need to understand the core concepts of NoSQL and MongoDB to contribute effectively to the project.

Learning Objectives

By the end of this lesson, you will be able to:

• Explain the differences between SQL and NoSQL databases.
• Describe the structure of MongoDB, including documents and collections.
• Interact with a MongoDB database using MongoDB Compass.

What is NoSQL?

NoSQL, which stands for “Not Only SQL,” refers to a type of database that is not built on the traditional relational (SQL) model. While SQL databases use tables, rows, and columns to structure data with a predefined schema, NoSQL databases use more flexible data models. This makes them ideal for applications that require high performance, scalability, and the ability to handle unstructured or semi-structured data.

Key Differences Between SQL and NoSQL

Introduction to MongoDB

MongoDB is one of the most popular NoSQL databases. It is a document-oriented database, which means it stores data in flexible, JSON-like documents. This model maps directly to objects in your application code, making it easy to work with.

Core Concepts

• Document: A document is the basic unit of data in MongoDB, similar to a row in a SQL database. It is a set of key-value pairs, where keys are strings and values can be various data types, including other documents and arrays.

  {
    "_id": "60c72b2f9b1e8a5f4d6e8b21",
    "title": "The Great Gatsby",
    "author": "F. Scott Fitzgerald",
    "year": 1925,
    "genres": ["Novel", "Fiction"]
  }

• Collection: A collection is a group of related documents, similar to a table in a SQL database. However, unlike a table, a collection does not enforce a strict schema. This means the documents within a single collection can have different fields.

• Database: A database is a container for collections. Each database gets its own set of files on the file system. A single MongoDB server can host multiple databases.

Activities

Activity 1: Explore a Database with MongoDB Compass

MongoDB Compass is a graphical user interface (GUI) that allows you to interact with your MongoDB data without writing scripts. In this activity, you will connect to a sample database and explore its collections and documents.

1. Download and Install MongoDB Compass: If you haven’t already, download it from the MongoDB website .
2. Connect to a Sample Cluster: Open Compass and use the following connection string to connect to a read-only sample dataset:

mongodb+srv://ps-learner:read-only-access@cluster0.4fx7ve3.mongodb.net/

3. Explore Collections: Once connected, you will see a list of databases. Navigate into the sample_mflix database.

4. Inspect Documents: Click on the movies collection. Browse through the documents and observe their structure. Notice how some documents have fields that others do not.

5. Filter Data: Use the filter bar at the top to query the data. For example, try to find all movies released in the year 1999 by using the following filter:

   { "year": 1999 }

Knowledge Check

Summary

In this lesson, you learned about the fundamental concepts of NoSQL databases and how they differ from traditional SQL databases. You were introduced to MongoDB’s document-oriented model, including its core components: documents, collections, and databases. Finally, you gained hands-on experience by exploring a sample database with MongoDB Compass. This foundation will be crucial as you move on to building applications with MongoDB.

References

• MongoDB: NoSQL Explained 
• MongoDB Manual: Documents 
• MongoDB Manual: Databases and Collections 
• MongoDB Compass Documentation 

Additional Resources

• MongoDB University: Introduction to MongoDB 
• Data modeling in MongoDB