LISTING 4: Query That Returns Latest and Previous Contract
Details (ANSI Subquery 

Solution)
SELECT
  custid,
  cdate,
  amount,
  (SELECT amount
   FROM Contracts AS C2
   WHERE C2.custid = C1.custid
     AND cdate = (SELECT MAX(cdate)
                  FROM Contracts AS C3
                  WHERE C3.custid = C1.custid
                    AND C3.cdate < C1.cdate)) AS prev_amount
FROM Contracts AS C1
WHERE cdate = (SELECT MAX(cdate)
               FROM Contracts AS C4
               WHERE C4.custid = C1.custid)