SQL — Structured Query Language

Learn SQL by reasoning about data

This course treats SQL as a declarative, set-oriented language: describe the result you need, then let the database plan how to produce it. Begin with why relational databases exist, then learn table design, querying, filtering, aggregation, functions, data changes, set operations, joins, privileges, and transactions.

The examples are primarily MySQL-oriented where dialect differences matter. SQL syntax and behavior vary between database systems, so the lessons call out portability rather than implying every example works unchanged everywhere.

Start with Chapter 1: Why SQL Exists.