CREATE TABLE customer_orders (customer_id VARCHAR2, order_date VARCHAR2)
CREATE TABLE customers (customer_name VARCHAR2, customer_id VARCHAR2)

Who made the latest order?
SELECT t1.customer_name FROM customers AS t1 JOIN customer_orders AS t2 ON t1.customer_id = t2.customer_id ORDER BY t2.order_date DESC LIMIT 1
SELECT "t1"."customer_name" FROM "customers" "t1" JOIN "customer_orders" "t2" ON "t1"."customer_id" = "t2"."customer_id" ORDER BY "t2"."order_date" DESC FETCH FIRST 1 ROWS ONLY