7. Grouping and Filtering

This module teaches you how to summarize datasets and filter aggregate results without breaking query correctness.

Decision Guide

Goal	Clause to use	Why
Group rows by one or more keys	GROUP BY	Produces aggregate result sets
Filter rows before grouping	WHERE	Reduces input rows early
Filter grouped results	HAVING	Applies conditions after aggregation
Produce subtotals/grand totals	ROLLUP / GROUPING SETS	Reporting-friendly totals

Lessons

• GROUP BY
• HAVING Clause
• GROUP BY with ROLLUP / GROUPING SETS

What's Next

• Continue to 8. Advanced SQL Features