play area...see if this makes any sense and can be worked upon

SELECT TOP 1000000

TranDate = Dateadd(dd, Abs(Checksum(Newid()))%Datediff(dd, '2011', '2014'), '2011'),

ProdID = 1 + CAST(Abs(Checksum(Newid()) % 50000 ) AS INT),

Qty = CAST(Rand(Checksum(Newid())) * 99 + 1 AS INT)

INTO Transdata

FROM sys.all_columns ac1

CROSS JOIN sys.all_columns ac2

CROSS JOIN sys.all_columns ac3

GO

CREATE CLUSTERED INDEX [CIX] ON [dbo].[TransData]

([ProdID] ASC, [TranDate] ASC )

GO

SELECT DATEADD ( MONTH , -1 * N , DATEADD ( mm , DATEDIFF ( mm , 0 , GETDATE ( )) , 0 )) AS TranDate

INTO jlsdates

FROM Tally t

WHERE N >= 1

AND N <= 24;

CREATE CLUSTERED INDEX [CIX] ON [dbo].[jlsdates]

([TranDate] ASC)

;with jlscte as

(

SELECT jlsdates.TranDate

, TransData.ProdID

, SUM ( TransData.qty ) AS cumtot

FROM

jlsdates LEFT OUTER JOIN TransData

ON jlsdates.TranDate > TransData.TranDate

GROUP BY TransData.ProdID

, jlsdates.TranDate

)

SELECT ProdID, TranDate, cumtot

FROM jlscte

WHERE

(ProdId =1500)

order by tranDate