Table schema:
CREATE TABLE invoices (total INTEGER, customer_id VARCHAR); CREATE TABLE customers (first_name VARCHAR, last_name VARCHAR, id VARCHAR)

Question: List the top 10 customers by total gross sales. List customers' first and last name and total gross sales.
SQL: SELECT T1.first_name, T1.last_name, SUM(T2.total) FROM customers AS T1 JOIN invoices AS T2 ON T2.customer_id = T1.id GROUP BY T1.id ORDER BY SUM(T2.total) DESC LIMIT 10