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

Question: Find out 5 customers who most recently purchased something. List customers' first and last name.
SQL: SELECT T1.first_name, T1.last_name FROM customers AS T1 JOIN invoices AS T2 ON T2.customer_id = T1.id ORDER BY T2.invoice_date DESC LIMIT 5