SQL - suma acumulada

SELECT BusinessEntityID, TerritoryID

    ,CONVERT(varchar(20),SalesYTD,1) AS  SalesYTD

    ,DATEPART(yy,ModifiedDate) AS SalesYear

    ,CONVERT(varchar(20),SUM(SalesYTD) OVER (PARTITION BY TerritoryID

                                             ORDER BY DATEPART(yy,ModifiedDate)

                                             ROWS UNBOUNDED PRECEDING),1) AS CumulativeTotal

FROM Sales.SalesPerson

WHERE TerritoryID IS NULL OR TerritoryID < 5;

BusinessEntityID TerritoryID SalesYTD             SalesYear   CumulativeTotal

---------------- ----------- -------------------- ----------- --------------------

274              NULL        559,697.56           2005        559,697.56

287              NULL        519,905.93           2006        1,079,603.50

285              NULL        172,524.45           2007        1,252,127.95

283              1           1,573,012.94         2005        1,573,012.94

280              1           1,352,577.13         2005        2,925,590.07

284              1           1,576,562.20         2006        4,502,152.27

275              2           3,763,178.18         2005        3,763,178.18

277              3           3,189,418.37         2005        3,189,418.37

276              4           4,251,368.55         2005        4,251,368.55

281              4           2,458,535.62         2005        6,709,904.17