Three tables in SQL
SQL interview exercise on Joins, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Return the revenue from each customer: the sum of quantity × unit_price over their orders, ignoring cancelled orders. Customers with no revenue do not appear. Columns: customer, revenue. Highest revenue first, then by customer.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.