Learn SQL Lesson

WHERE Filters Before GROUP BY

`WHERE` removes individual rows before any grouping or aggregation happens.

If you write:

SELECT region, SUM(amount) AS total_amount
FROM sales
WHERE amount >= 900
GROUP BY region

only sales with amount >= 900 participate in the grouped totals. Smaller rows are gone before `GROUP BY` ever runs.

This is why `WHERE` is for row-level filters, not group-level filters.

Practice challenge

Only consider sales with amount >= 900. Then return region and total_amount, ordered by region.