Oracle: Helping hand writing this query. Do I need a sub query here?
Using PIVOT:

WITH
   combined AS (
      SELECT
         o.customer_no,
         EXTRACT(month FROM o.entry_date) AS order_month, 
         EXTRACT(year FROM o.entry_date) AS order_year, 
         t.order_final_tot
      FROM orders o
      JOIN order_totals t ON (o.order_no = t.order_no)
   )
SELECT *
FROM combined
PIVOT (
   SUM(order_final_tot) AS ord_tot, 
   COUNT(*) AS ord_cnt
   FOR order_year IN (2013, 2014)
);