Sum by Region — Solution & ExplanationProblems / Sum by Region / EditorialApproachA direct application of SUM() with GROUP BY:

GROUP BY region to partition rows by region.

SUM(amount) to total the sales within each region.

ORDER BY region for a stable result.

Key ConceptSUM() ignores NULL values. If a group has only NULLs, the result is NULL (not 0).Hints

SUM() adds up all values in a group.

Make sure to alias your aggregated column as 'total_sales'.