← SQL Analyst Starter
Lesson 2 of 4
Group without losing rows
Aggregate revenue by a declared grouping key.
Do the work
- WHERE applies before GROUP BY.
- SUM(amount) totals whole-dollar amounts.
- COUNT(*) counts rows, including repeated values.
See the method
Filter paid orders.
Practice independently
Exercise 1
Calculate paid revenue by region
Open practice →Exercise 2Preserve repeated amounts
Open practice →Take it further
Compare COUNT(*) with COUNT(customer_id) when IDs can be NULL.