Introduction

“Those who know, do. Those that understand, teach.” —Aristotle

There are hundreds of SQL tutorials online to teach people SQL syntax. This book is not about syntax. This book is about building mental models around what SQL is doing and understanding why others struggle to understand so that it is easier to help them learn.

After teaching thousands of students the basics of SQL I understand their main sticking points:

• Confusion about what a database is
• How Joins work
• How Aggregations work
• How Subqueries work
• What to do about errors
• How to approach optimization

Understanding these abstract ideas comes naturally to engineers and analysts who work with code everyday. Business people tend to struggle with understanding what code is doing. They can’t quite conceptualize how the data is being transformed. They only see input and output.

This book will provide many graphics, animations, and explanations to help convey SQL to others. Use this book to better understand what will help other people at your organization learn SQL and use it as a resource to point them to when they get stuck.

We hope this book helps increase data literacy at your company!

Written by: Matt David
Reviewed by: Dave Fowler