Последнее положительное знач из массива

[NIKOLASCS]

СУБД MSSQL 2000

Сформировал запрос на 12 мес:
SELECT Cust.CustomerID, Cust.LicNumber, Cust.FirstName, Cust.TownName, Cust.StreetName, Cust.HouseNumber, Cust.Apartment, Customers.Litera, DevicesDict.Type, DevicesDict.Digits, DevicesDict.Accuracy, Devices.Number, DevicesDict.CurrentMax, DevicesDict.Num_phase, Devices.InstDate, MAX( CASE WHEN Month(bypass_sheet.SheetDate ) = 1 AND Year(bypass_sheet.SheetDate ) = 2010 THEN bypass_sheet_item.OldMeasure END ) AS [Янв.нач],MAX( CASE WHEN Month(bypass_sheet.SheetDate ) = 1 AND Year(bypass_sheet.SheetDate ) = 2010 THEN bypass_sheet_item.Measure END ) AS [Янв.кон]............... FROM DevicesDict FULL OUTER JOIN Customers INNER JOIN Cust ON Customers.CustomerID = Cust.CustomerID INNER JOIN Devices ON Customers.CustomerID = Devices.CustomerID INNER JOIN bypass_sheet_item ON Customers.CustomerID = bypass_sheet_item.CustomerID INNER JOIN bypass_sheet ON bypass_sheet_item.SheetID = bypass_sheet.SheetID ON DevicesDict.DeviceDictID = Devices.DeviceDictID WHERE (bypass_sheet_item.BypassDate <= CONVERT(DATETIME, '2011-01-31 00:00:00', 102)) AND (bypass_sheet_item.BypassDate >= CONVERT(DATETIME, '2010-01-01 00:00:00', 102)) AND (Devices.DeviceID IN (SELECT MIN(Devices.DeviceID) FROM Devices WHERE Devices.InstDate IN (SELECT MAX(Devices.InstDate) FROM Devices WHERE Cust.CustomerID = Devices.CustomerID) AND Cust.CustomerID = Devices.CustomerID))....

Как можно выбрать последнее положительное значение из массива bypass_sheet_item.OldMeasure + bypass_sheet_item.Measure + bypass_sheet_item.Consumption?