40. Spend per Customer Across Three Tables
HardJoinsthree-table joinGROUP BYSUM
Real schemas spread data across several tables. Here a customer has many orders, and each order has many line items. To total what each customer spent you must chain three joins, then aggregate.
Task: for each customer return their name and total_spent, the sum of qty * price over all line items across all their orders.
Output columns, in this exact order: customer, total_spent. Order by total_spent descending, breaking ties by customer ascending.
Tables
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Expected outputrows must come back in this order
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