CREATE TABLE invoices (customer_id VARCHAR)
CREATE TABLE customers (first_name VARCHAR, last_name VARCHAR, id VARCHAR)

Find out the top 10 customers by total number of orders. List customers' first and last name and the number of total orders.
SELECT T1.first_name, T1.last_name, COUNT(*) FROM customers AS T1 JOIN invoices AS T2 ON T2.customer_id = T1.id GROUP BY T1.id ORDER BY COUNT(*) DESC LIMIT 10
SELECT "T1"."first_name", "T1"."last_name", COUNT(*) FROM "customers" AS "T1" JOIN "invoices" AS "T2" ON "T1"."id" = "T2"."customer_id" GROUP BY "T1"."id" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 10