Listing 2: Solution Query for Problem 1
SELECT O1.empid, O1.ordermonth, O1.qty,
  SUM(O2.qty) AS totalqty, AVG(O2.qty) AS avgqty
FROM EmpOrders AS O1
  JOIN EmpOrders AS O2
    ON O2.empid = O1.empid
    AND O2.ordermonth <= O1.ordermonth
GROUP BY O1.empid, O1.ordermonth, O1.qty
ORDER BY O1.empid, O1.ordermonth