ช่วยทีครับ ใช้คำสั่ง group by แต่ไม่ได้ผลลัพธ์อย่างที่ต้องการ ช่วยดูให้ทีครับ

<script language = "JavaScript">

		//**** List Province (Start) ***จังหวัด//
		function ListProvince(SelectValue)
		{
				frmMain.ddlProvince.length = 1
			    frmMain.ddlAmphur.length = 1
			//*** Insert null Default Value ***//
	
			<?php
			$intRows = 0;
			$strSQL1 = "SELECT * FROM datacar GROUP BY data_gene ORDER BY data_gene ASC";
			$objQuery1 = mysql_query($strSQL1) or die ("Error Query [".$strSQL1."]");
			$intRows = 0;
			while($objResult1 = mysql_fetch_assoc($objQuery1))
			{
			$intRows++;
			
			?>			
				x = <?=$intRows;?>;
				mySubList = new Array();
				
				strGroup = "<?=$objResult1["data_brand"];?>";
				strValue = "<?=$objResult1["data_gene"];?>";
				mySubList[x,0] = strGroup;
				mySubList[x,1] = strValue;
				if (mySubList[x,0] == SelectValue){
					var myOption = new Option(mySubList[x,1])
					frmMain.ddlProvince.options[frmMain.ddlProvince.length]= myOption
									
				}
			<?php
			}
			?>																	
		}
		//**** List Province (End) ***//

		
		//**** List Amphur (Start) ***อำเภอ//
		function ListAmphur(SelectValue)
		{
			
		    frmMain.ddlAmphur.length = 1
			//*** Insert null Default Value ***//
			
			<?php
			$intRows = 0;
			$strSQL1 = "SELECT * FROM datacar GROUP BY data_year ORDER BY data_year ASC";
			$objQuery1 = mysql_query($strSQL1) or die ("Error Query [".$strSQL1."]");
			$intRows = 0;
			while($objResult1 = mysql_fetch_array($objQuery1))
			{
			$intRows++;
			?>
				x = <?=$intRows;?>;
				mySubList = new Array();
				
				strGroup = "<?=$objResult1["data_gene"];?>";
				strValue = "<?=$objResult1["data_year"];?>";
				mySubList[x,0] = strGroup;
				mySubList[x,1] = strValue;			
				
				if (mySubList[x,0] == SelectValue){
					var myOption = new Option(mySubList[x,1])  
					frmMain.ddlAmphur.options[frmMain.ddlAmphur.length]= myOption					
				}
				
			<?php
			}
			?>																	
		}
		//**** List Amphur (End) ***อำเภอ//

		//**** List District (Start) *** ตำบล//
		//**** List District (End) ***ตำบล//

</script>
<form name="frmMain" action="" target="_self" method="post"><select id="ddlGeo" name="ddlGeo"  onChange = "ListProvince(this.value)" type="text"><label for="text1">ค้นหา :</label>
 
	<option value="" ><-- เลือกยี่ห้อ --></option>
            <?php
			$strSQL1 = "SELECT * FROM datacar GROUP BY data_brand ORDER BY data_brand ASC";
			$objQuery1 = mysql_query($strSQL1);
			while($objResult1 = mysql_fetch_array($objQuery1))
			{
			?>
            <option value="<?php echo $objResult1["data_brand"];?>"><?php echo $objResult1["data_brand"];?></option>
            <?php
			} 
			?> 
            </select>
        <tr>
    <th scope="col" width="50" align="left" style="color:#000">แบบ(รุ่น)</th>
    <th scope="col" width="244" align="left"><select id="ddlProvince"   name="ddlProvince"  onChange= "ListAmphur(this.value)"><option value="" ><-- เลือกแบบ(รุ่น) --></option></select><tr>
    <th scope="col" width="50" align="left" style="color:#000">ปี</th>
    <th scope="col" width="244" align="left"><select id="ddlAmphur"  name="ddlAmphur" ><option value=""><-- เลือกปี --></option></select>
     <th scope="col" width="50" align="left"><input name="btnsearch1" type="submit" value="search !" /></th> </form>