SQL Course

This course teaches practical SQL for developers who read, debug, and review queries. It is not a database administration manual and not a vendor-specific certification track. The goal is to help you understand the structure of SQL you see in logs, ORMs, dashboards, pull requests, and incident debugging.

You will learn how to read a query from the outside in, how filters and joins change result sets, why aggregation often surprises teams, and how formatting makes a dense query easier to reason about.

Who this course is for

• Backend engineers reviewing ORM output, slow query logs, and data access code
• Full-stack developers who need to understand API behavior through database queries
• Data-adjacent developers who write reporting queries but want safer debugging habits

What you will learn

1. SQL as a declarative language for relational data
2. The everyday shape of SELECT, WHERE, ORDER BY, and LIMIT
3. How joins affect result rows and why duplicates appear
4. Aggregation with GROUP BY, HAVING, and time buckets
5. Formatting patterns that make long SQL readable in reviews
6. A practical debugging workflow for logs, ORM output, and dialect differences

Use the related SQL Formatter to format examples locally while you read. Formatting does not execute a query or prove database semantics, but it makes the structure visible enough to reason about.