เป็นมือใหม่ค่ะ แก้ไม่ค่อยคล่อง ช่วยหน่อยนะคะ ขอคำแนะนำด้วยค่ะ

<?	
$page=$_GET[page];
if ($page=="") {
	$page=1;
}
$each=15;

$sql_item = "SELECT * FROM tbstudents ;";
$result_item = mysql_query($sql_item);
$totals = mysql_num_rows($result_item);

$totalpages=ceil($totals/$each);
$goto = ($page-1)*$each;

$sql_item = "SELECT * FROM tbstudents order by itemid desc limit $goto,$each;";
$result_item = mysql_query($sql_item);

$sql="Select  max(studentsid) as maxitemId from tbstudents  ";
$result=mysql_db_query($dbname, $sql);
$dbarr=mysql_fetch_array($result);
	if ($dbarr) {
		$total=$dbarr['maxitemId']+1;
		if  (strLen($total)=="1" ) {
			$total= "0" .$total;
		} else {
			$total= $total;		
		}
	} else {
		$total= $itemId ;
	}
?>

<form method="post" action="students_action.php?do=add" enctype="multipart/form-data">
<table width="100%" border=0 align=center cellPadding=2 cellSpacing=0>
  <tr bgColor=#FFCC99>
    <td colspan="2" bgcolor="#FF9900" ><strong>:: เพิ่มข้อมูลนักศึกษาหอพัก ::</strong></td>		
	</tr>	
  <tr>
    <td align="right">รหัสนักศึกษา</td>
    <td><label>
    <input type="text" name="studentsid" id="textfield" /></label></td>		
	</tr>	
  <tr>
    <td align="right">หอพัก</td>
    <td>
	  <select name="ref_Dormid">
		<option value="0">กรุณาเลือกหอพัก</option>
			<?
			$sql_dorm="select * from tbDorm";
			$result_dorm = mysql_query($sql_dorm);
			while($dbarr_dorm=mysql_fetch_array($result_dorm)) {
				echo "<option value=" . $dbarr_dorm['Dormid'] . ">" . $dbarr_dorm['Dormname'] . "</option>";
			}
			?>
	</select>
	  *</td>		
	</tr>	
  <tr>
    <td align="right">ห้องพัก</td>
    <td>
		<select name="ref_Badid">
			<option value="0">กรุณาเลือกห้องพัก</option>
			<?
			$sql="select * from tbbad";
			$result = mysql_query($sql);
			while($dbarr_bad=mysql_fetch_array($result)) {
				echo "<option value=" . $dbarr_bad['Badid'] . ">" . $dbarr_bad['Badname'] . "</option>";
			}
			?>
		</select> 
		*	
	</td>		
	</tr>	        
  <tr>
    <td align="right">ชื่อ - นามสกุลนักศึกษา</td>
    <td><INPUT maxLength=50  name=namestudents> 
    *</td>		
	</tr>
  <tr>
    <td align="right">รายละเอียด</td>
    <td><textarea name="detail" cols="40" rows="4"></textarea> 
    *</td>		
	</tr>	        
  <tr>
    <td align="right">ราคาค่าห้องพัก</td>
    <td><INPUT maxLength=50 name=itemprice size="8"> 
    บาท *</td>		
	</tr>	    
    <tr>
      <td align="right">ไฟล์รูปภาพ</td>
      <td><input type="file" name="photo"><input type="hidden" name="MAX_FILE_SIZE" value="100000"></td>
    </tr>	    
	<tr>
		<td colspan="2" align="right">
          <div align="center">
			<INPUT type="submit" value="บันทึก" name="submit">
            <input type="reset" name="reset" value="ล้างข้อมูล">					
            <input type="hidden" name="itemNo" value="<?=$total; ?>">	
          </div></td>
	</tr>	
</table>
</form>

<table width="100%" border=0  align=center cellPadding=2 cellSpacing=0>
  <tr bgColor=#FFCC99>
    <td bgcolor="#FF9900"><div align="center"><strong>รหัสนักศึกษา</strong></div></td>
    <td bgcolor="#FF9900"><div align="center"><strong>ชื่อ - นามสกุล</strong></div></td>		
    <td bgcolor="#FF9900"><div align="center"><strong>หอพัก</strong></div></td>		    	    
    <td bgcolor="#FF9900"><div align="center"><strong>แก้ไข</strong></div></td>
    <td bgcolor="#FF9900"><div align="center"><strong>ลบ</strong></div></td>
	</tr>

<?
 while ($dbarr_item = mysql_fetch_array($result_item)) { //ฟ้องว่าบรรทัดนี้ error ค่ะ Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in C:\AppServ\www\Dorm2\admin\addstudents.php on line 129
?>	
  <tr>
    <td align="center" width="10%"><? echo $dbarr_item['studentsid'] ?></td>
    <td><? echo $dbarr_item['namestudents'] ?></td>
    <td>
		<?
		$sql1="select * from tbdorm where dormid='$dbarr_dorm[ref_Dormid]'";
		$result1 = mysql_query($sql1);
		$dbarr1=mysql_fetch_array($result1);
		echo $dbarr1['Dormname'];
		?>
	</td>		    	    		
    <td align="center" width="15%">[<a href="students_action.php?do=frmedit&id=<? echo $dbarr_item['studentsid'] ?>">แก้ไข</a>]</td>
    <td align="center" width="15%">[<a href="students_action.php?do=delete&id=<? echo $dbarr_item['studentsid'] ?>">ลบ</a>]</td>
	</tr>	
<?
}
?>
	<tr>
		<td align="center"></td>
		<td colspan="4" align="right">รวมทั้งหมด  <?=$totals?> รายการ : 
		<?
		if ($totalpages>1) {
			for ($i=1;$i<=$totalpages;$i++) {
				if ($i == $page) {
					echo "<b>หน้า $page</b>";
				} else {
					echo " | <a href=\"addstudents.php?page=$i\">$i</a>&nbsp;";
				}
			}
		}
		?>
		</td>
	</tr>	
</table>
<script type="text/javascript">
<!--
var sprytextfield1 = new Spry.Widget.ValidationTextField("sprytextfield1");
//-->
</script>