ถามเรื่อง GROUP BY Month ที่ครับ....งม มานาน แสนนาน แล้วครับ ช่วยหน่อยนะครับ

SELECT  SUM(b.iMoney) AS IMONEY
       FROM     SaleBillVouch AS a right OUTER JOIN
       SaleBillVouchs AS b ON a.SBVID = b.SBVID      
       WHERE  (a.dDate BETWEEN '$startdate' AND '$enddate') 
       AND        b.cInvCode = '$id'"       
      group by date_format(a.dDate,'%m')

<?
$id = $_REQUEST['txtid'];
	$startdate = $_GET['txtstart'];
	$enddate = $_GET['txtend'];
$strSQL = "SELECT SUM(b.iMoney) AS IMONEY,
SUM(b.iQuantity) AS IQTY,
CONVERT(char(10), a.dDate, 103) AS 'months'
FROM SaleBillVouch AS a RIGHT OUTER JOIN 
SaleBillVouchs AS b ON a.SBVID = b.SBVID
WHERE (a.dDate BETWEEN '$startdate' AND '$enddate') 
AND b.cInvCode = '$id'
GROUP BY CONVERT(char(10), a.dDate, 103)";
$objQuery = mssql_query($strSQL) or die ("Error Query [".$strSQL."]");

?>
<table width="600" border="1">
  <tr>
    <th width="91"> <div align="center">วันที่เปิดบิล </div></th>
    <th width="98"> <div align="center">ราคาที่ขาย </div></th>
    <th width="198"> <div align="center">จำนวนที่ขาย </div></th>

  </tr>
<?
while($objResult = mssql_fetch_array($objQuery))
{
?>
  <tr>
    <td><div align="center"><?=$objResult["months"];?></div></td>
    <td><?=$objResult["IMONEY"];?></td>
    <td><?=$objResult["IQTY"];?></td>

  </tr>
<?
}
?>
</table>
<?
mssql_close($objConnect);
?>
</body>
</html>

<td><div align="center"><? echo date_format($objResult["months"],'m/y');?></div></td>

SELECT RIGHT(CONVERT(VARCHAR(10), GETDATE(), 103), 7) AS [MM/YYYY]

"SELECT SUM(b.iMoney) AS IMONEY,
SUM(b.iQuantity) AS IQTY,
COUNT(*) as Imonths,
DATEADD(month, DATEDIFF(month, 0, a.dDate),103)AS Imonths
FROM SaleBillVouch AS a RIGHT OUTER JOIN 
SaleBillVouchs AS b ON a.SBVID = b.SBVID
WHERE (a.dDate BETWEEN '$startdate' AND '$enddate') 
AND b.cInvCode = '$id'
GROUP BY DATEADD(month, DATEDIFF(month, 0, a.dDate),103)"