The Ultimate SQL Mastery
A path from your first SELECT to window functions, query plans and warehouse-scale modelling.
SQL, end to end. Not a syntax reference — a path from writing your first query to reasoning about how a database executes it.
Every lesson is free and needs no sign-up. Work through the modules in order if you are starting out; jump straight to what you need if you are not.
Syllabus
Foundations
SELECT, filtering, ordering, and the mental model of a relation.
Combining data
Joins, set operations, and why the join order in your head is not the planner's.
Aggregation
Grouping, HAVING, and the difference between filtering rows and filtering groups.
Window functions
Ranking, running totals, and frame clauses.
Modelling
Normalisation, dimensional design, and when to break the rules deliberately.
Performance
Indexes, query plans, and reading EXPLAIN without guessing.