01
Database Overview
The foundations: databases, the main database types, SQL and NoSQL.
MongoDB Tutorial
Learn MongoDB step by step, from what a database is to backups and replica sets in production. Plain explanations, hands-on mongosh commands and Java examples, updated for MongoDB 8.0.
- 22 tutorials
- 7 learning tracks
- mongosh & Java code
- Beginner to advanced
What Is MongoDB?
MongoDB is a general-purpose document database. Instead of rows in tables, it stores data as flexible, JSON-like documents that look just like the objects in your code. It adds powerful queries and aggregation, indexes, automatic failover with replica sets, horizontal scaling with sharding, and ACID transactions, which is why it runs everything from small side projects to some of the largest applications in the world.
TypeDocument database (NoSQL)
First release2009
Current major versionMongoDB 8.0
Data formatBSON (binary JSON)
What You Will Learn
- What databases, SQL and NoSQL are, and how they differ
- How MongoDB stores data in databases, collections and documents
- Creating, renaming and dropping databases and collections
- Inserting, querying, updating and deleting documents (CRUD)
- Query operators, projection, sorting and aggregation basics
- Designing indexes with the ESR rule and reading
explain() - Replica sets, elections, write concern and read preference
- Backing up and restoring data safely
- Answering common MongoDB interview questions
Who this is for
Students and beginners new to databases, Java and Spring Boot developers adding MongoDB to their stack, and engineers preparing for interviews.
Prerequisites
Basic computer and command-line skills. Some JavaScript or Java helps with the code examples, but the first tracks need no programming at all.
How MongoDB Organizes Data
A MongoDB deployment holds databases; each database holds collections; each collection holds documents. Documents in the same collection can have different fields, and each one has a unique _id.
Deployment
Replica set rs0
Databases: bookstore, analytics
bookstore.books collection
{ _id: 101, title: "Practical Java Streams",
price: 499, tags: ["java", "streams"] }
{ _id: 102, title: "Designing Event Systems",
price: 650, publisher: { country: "US" } }
Indexes keep queries fast
Your app
mongosh
Java driver
Spring Data
MongoDB Learning Path
Follow the tracks in order, or jump straight to the topic you need. Each tutorial explains the idea in simple words and then shows working commands.
02
MongoDB Overview
What MongoDB is, what it can do and how it compares with MySQL.
03
Databases
Create and remove databases, with naming rules and safety tips.
04
Collections
Validation, time series, capped and clustered collections, views and renames.
05
CRUD Operations
Insert, query, update and delete documents, with operators and Java examples.
06
Advanced Topics
Performance, high availability and protecting your data.
07
Reference & Interview
A command cheat sheet and 40 interview questions with answers.
Quick Start: MongoDB in Five Minutes
Run MongoDB 8.0 locally with Docker, connect with mongosh and store your first document. (Prefer the cloud? Create a free cluster on MongoDB Atlas and use its connection string instead.)
docker run -d --name mongo8 -p 27017:27017 mongo:8.0
docker exec -it mongo8 mongoshuse bookstore
db.books.insertOne({ title: "Practical Java Streams", category: "Java", price: 499 })
db.books.find({ price: { $lt: 600 } })
db.books.updateOne({ title: "Practical Java Streams" }, { $inc: { price: -50 } })
db.books.countDocuments()The bookstore database and books collection were created automatically by the first insert. Continue with the MongoDB Introduction to understand what just happened.
Why Developers Choose MongoDB
Natural Data Model
Documents map directly to objects in code, with nested fields and arrays, so there is no translation layer.
Flexible Schema
Add fields without migrations, and enforce rules with JSON Schema validation where it matters.
Powerful Queries
Filter on any field, aggregate with pipelines, and add full-text and vector search on Atlas.
High Availability
Replica sets keep copies on several servers and fail over automatically within seconds.
Horizontal Scaling
Sharding spreads data and writes across many servers as your application grows.
Transactions & Security
ACID transactions, role-based access control, TLS and Queryable Encryption.
Coming from SQL?
Most relational ideas have a direct MongoDB equivalent:
| SQL | MongoDB |
|---|---|
| Database | Database |
| Table | Collection |
| Row | Document |
| Column | Field |
SELECT … WHERE | find({ … }) |
INSERT / UPDATE / DELETE | insertOne() / updateOne() / deleteOne() |
GROUP BY | $group in an aggregation pipeline |
JOIN | Embedded documents or $lookup |