SELECT BusinessEntityID, DATEPART(YEAR, QuotaDate) AS SalesYear, SalesQuota AS CurrentQuota,   
       LAG(SalesQuota, 1, 0) OVER (ORDER BY DATEPART(YEAR, QuotaDate)) AS PreviousQuota  
FROM Sales.SalesPersonQuotaHistory  
WHERE BusinessEntityID = 275 AND DATEPART(YEAR, QuotaDate) IN (2012, 2013);

