SQL
Mastery.

SELECT, WHERE, ORDER BY, LIMIT and filtering results.

Aggregate functions (COUNT, SUM, AVG) and GROUP BY.

INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN.

Multiple joins and relationships between tables.

Subqueries, CTEs, UNION and views.

Window functions, HAVING and complex cases.

Data cleaning, handling missing values and outliers.

Exploratory analysis with SQL and query optimisation.

Indexes, EXPLAIN, performance tuning.

Complete data analysis project + presentation.