Let me be direct about what this is — and what it is not.
There are hundreds of "learn SQL" tutorials on the internet. Most teach you a SELECT statement in isolation, celebrate that, and leave you there. You finish, open a real job description, and suddenly you're reading about dbt, Snowflake, partitioning, ETL pipelines, data lakes, vector stores, and AI agents — none of which the tutorial mentioned.
The 90-Day Data Quest was built to close that gap completely. One structured path, 90 days, from SELECT * FROM table all the way to an AI agent that queries your database autonomously.
"The goal is not to teach you SQL. The goal is to make you the kind of engineer who can look at any data problem — from a simple report to an AI agent querying a lakehouse — and know exactly what to do."
What Is The 90-Day Data Quest?
The 90-Day Data Quest is a free, open-source, project-driven curriculum that teaches the entire modern data stack as one connected journey over 90 days — not ten disconnected courses. The idea is simple: treat learning data like a quest, with a clear destination and a path you actually finish. Every concept is taught in context. Every technology is explained through its relationship to everything else.
You won't just learn SQL here and data engineering somewhere else and Snowflake in a vendor tutorial. You'll see how a decision made at the SQL layer has consequences six layers up in an AI system. When you finish, you won't have a pile of disconnected skills. You'll have a mental model of how the whole thing fits together.
What This Series Offers
Every module is hands-on. You don't watch — you build. Here's what's inside each one:
Real Datasets
Every module ships with realistic datasets and ready-to-run setup scripts — no toy examples.
Business Scenarios
You solve problems for a fictional company, DataVerse Inc. — the way real work actually arrives.
Runnable Code
Every query and script is in the GitHub repo. Clone it, run it, break it, learn from it.
Progressive Exercises
Each module ends with exercises that get harder — plus solutions so you can check your work.
Capstone Projects
Build complete platforms: HR analytics, sales intelligence, a warehouse, an AI data agent.
Everything Connected
Each module explicitly links back to the ones before — so the knowledge compounds.
Who This Series Is For
The 90-Day Data Quest meets you wherever you are. It works whether you've never written a query or you've been a data engineer for years and want to understand the AI layer being built on top of your work.
Complete Beginners
Never written SQL? Start at the very first module. No prerequisites.
Career Switchers
Moving into data from another field — get a complete, structured path.
Data & BI Analysts
Know basic SQL but never built a pipeline or warehouse? This fills the gap.
Software Engineers
Want to move into data engineering with a solid foundation, not guesswork.
Data Engineers
Strengthen the fundamentals and understand the AI systems on top of your data.
AI Engineers
Understand how structured data actually works at scale — the layer your models depend on.
What You'll Achieve
This is the concrete outcome. By the time you finish the 90-Day Data Quest, you will be able to:
- Write SQL that would pass a senior data engineer interview at any major tech company
- Design and build a data warehouse from scratch — schema, facts, dimensions, slowly changing dimensions
- Build production data pipelines using Python and PySpark
- Architect and deploy a complete Snowflake-based analytics platform
- Design BI dashboards that answer real business questions, not just display numbers
- Understand how MPP (Massively Parallel Processing) engines work and when to use them
- Build AI-powered data systems — including RAG pipelines and Text-to-SQL agents
- Design an Agentic Data System where AI autonomously queries, analyzes, and acts on data
The Full Stack — One Connected Journey
Here's the mental model the whole series is built on. SQL is not one layer among many. It's the language every layer above it is ultimately written in.
The Learning Modules
The journey is split into five phases built on top of each other. You can't build a warehouse without SQL. You can't build an AI agent without understanding the data it queries. The sequence is deliberate.
Each module below links to its own folder in the GitHub repository. SQL is available now — the rest are being published in sequence. Bookmark this page; the links go live as each module ships.
The GitHub Repository
Everything — every SQL script, dataset, exercise, and project — lives in one public repository. Clone it, run it, fork it, build on it.
All scripts, datasets, exercises, and projects are published at:
github.com/MuditKumarR/dataquest90
Each module corresponds to a folder in the repo. The README has the full index. Star the repo to follow along as new modules ship.
How to Start
What You Need
- PostgreSQL 15+ — free, runs on Windows, Mac, and Linux. Setup guides are in the repo.
- DBeaver or pgAdmin — a free GUI to run your queries.
- Git — to clone the repository and pull new modules as they ship.
- Python 3.11+ — needed from the Data Engineering module onward. Not required for SQL.
Your First Step
- Clone the repo:
git clone https://github.com/MuditKumarR/dataquest90 - Open
README.mdfor the full index and setup instructions - Start with Module 01 — SQL Fundamentals (available now)
- Run the scripts, complete the exercises, check your answers in the solutions folder
git clone https://github.com/MuditKumarR/dataquest90 — then open Module 01 and write your first query. Day 1 of 90 starts here.
If you have ever looked at a data engineering job description and felt like you were reading a foreign language, the 90-Day Data Quest will translate every word of it. Start the first module today — and star the GitHub repository so you know when the next one ships.