SQL หาผลรวม แต่ละเดือน

SELECT DATEPART(Year ,DateCol) As 'Year' 
                  ,DATEPART(Month ,DateCol) As 'MTH'
                 ,Round(SUM(YourDataColumn),2) As 'kWh'
FROM YourTable
WHERE ...YourCriteria
GROUP BY DATEPART(Year ,DateCol) , DATEPART(Month ,DateCol)