Harvard's free programming classes teach you how to think, debug, and adapt in an AI-driven world where knowing code matters more than ever.

Advanced SQL for Data Analytics. A collection of problem-solving solutions covering complex Joins, Window Functions, CTEs, and Query Optimization. Includes real-world interview questions, schema ...

Aggregate functions help turn large datasets into simple summaries used across many fields. GROUP BY and HAVING allow structured grouping and filtering of data for clearer reports. Functions like ...