ช่วยดูที ครับ ลบได้ แก้ไข้ไม่ได้ ช่วยหาหน่อยว่าผิดตรงไหน

"UPDATE project SET  Project_Name =$Project_Name where Project_ID =$ProID";

Echo $_GET[Action];

<?
include "config.in.php";
$ProID=$_GET["ProID"] ;
$StuID=$_GET["StuID"] ;
$Project_Name=$_POST["Project_Name"] ;
if($_GET["Action"] == "Update")
{
	$strSQL = "UPDATE project SET  Project_Name ='$Project_Name' where Project_ID='$ProID'";
	$objQuery = mysql_query($strSQL);
	if(!$objQuery)

	{
		echo "Error Update [".mysql_error()."]";
	}
	header("location:$_SERVER[PHP_SELF]");
	exit();
}
if($_GET["Action"] == "Del")
{
	$strSQL1 = "DELETE FROM project WHERE Project_ID=$ProID AND Student_ID = $StuID ";
        $query1 = mysql_query($strSQL1) or die('Error Delete ['.mysql_error().']');

	$strSQL2="UPDATE student SET Project_ID=0 WHERE Student_ID=$StuID";
	$objQuery = mysql_query($strSQL2);

	if(!$objQuery)
	{
		echo "Error UPDATE [".mysql_error()."]";
	}
	header("location:$_SERVER[PHP_SELF]");
	exit();
}
?>
  <form id="form1" method="post" action="">
        <table width="100%" border="0">
              <tr>
                <td align="center"> <span class="style1">ค้นจาก
                    <select name="by" class="style1" id="by">
                      <option value="Project_Name" selected="selected">ชื่อโครง</option>
                      <option value="Proect_Term ">ภาคเรียน</option>
                        </select>
                </span>                  <span class="style1">คำที่ใช้ค้นหา</span>
                  <input type="text" name="keyword" id="keyword" /> 
                <input name="button" type="submit" class="style1" id="button" value="  ค้นหาชื่อโครงงาน  " /></td>
          </tr>
            </table>
      </form>
	  <?
		if($keyword==""){
		$strSQL="SELECT project. * , student.Student_ID
FROM project, student
WHERE project.Project_ID = student.Project_ID
AND project.Project_ID >0";
		}else{
		$strSQL="SELECT project. * , student.Student_ID
FROM project, student
WHERE project.Project_ID = student.Project_ID
AND project.Project_ID >0  AND $by like '%$keyword%' ";
		}
$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
$Num_Rows = mysql_num_rows($objQuery);

$Per_Page = 10;   // Per Page

$Page = $_GET["Page"];
if(!$_GET["Page"])
{
	$Page=1;
}

$Prev_Page = $Page-1;
$Next_Page = $Page+1;

$Page_Start = (($Per_Page*$Page)-$Per_Page);
if($Num_Rows<=$Per_Page)
{
	$Num_Pages =1;
}
else if(($Num_Rows % $Per_Page)==0)
{
	$Num_Pages =($Num_Rows/$Per_Page) ;
}
else
{
	$Num_Pages =($Num_Rows/$Per_Page)+1;
	$Num_Pages = (int)$Num_Pages;
}

$strSQL .=" order  by Project_Year ASC LIMIT $Page_Start , $Per_Page";
$objQuery  = mysql_query($strSQL);

?>

<form name="formadd" method="post" action="<?=$_SERVER["PHP_SELF"];?>">
<input type="hidden" name="hdnPro" value="">
<table width="600" border="1" align="center">
  <tr>
    <th width="91"> <div align="center">CustomerID </div></th>
    <th colspan="5"> <div align="center">Name </div></th>
    <th width="30"> <div align="center">Edit </div></th>
    <th width="30"> <div align="center">Delete </div></th>
  </tr>
<?
while($objResult = mysql_fetch_array($objQuery))
{
?>

  <?
	if($objResult["Project_ID"] == $_GET["ProID"] and $_GET["Action"] == "Edit")
	{
  ?>
  <tr>
    <td><div align="center">
	<?=$objResult["Project_ID"];?>
		<input type="hidden" name="hdnProID" size="5" value="<?=$objResult["Project_ID"];?>">
	</div></td>
    <td colspan="5"><input type="text" name="Project_Name" size="20" value="<?=$objResult['Project_Name'];?>"></td>
    <td colspan="2" align="right"><div align="center">
      <input name="btnAdd" type="button" id="btnUpdate" value="Update" OnClick="formadd.hdnProID.value='Update';formadd.submit();">
	  <input name="btnAdd" type="button" id="btnCancel" value="Cancel" OnClick="window.location='<?=$_SERVER["PHP_SELF"];?>';">
    </div></td>
  </tr>
  <?
	}
  else
	{
  ?>
  <tr>
    <td><div align="center"><?=$objResult["Project_ID"];?></div></td>
    <td colspan="5"><?=$objResult["Project_Name"];?></td>
    <td align="center"><a href="<?=$_SERVER["PHP_SELF"];?>?Action=Edit&ProID=<?=$objResult["Project_ID"];?>&StuID<?=$objResult["Student_ID"];?>">Edit</a></td>
	<td align="center"><a href="JavaScript:if(confirm('Confirm Delete?')==true){window.location='<?=$_SERVER["PHP_SELF"];?>?Action=Del&ProID=<?=$objResult["Project_ID"];?>&StuID<?=$objResult["Student_ID"];?>';}">Delete</a></td>
  </tr>
  <?
	}
  ?>
<?
}
?>
  <tr>
    
  </tr>
</table>
<div align="center"><br>
    <span class="style1">ทั้งหมด 
  <span class="style12">
    <?= $Num_Rows;?>
    </span> 
  จำนวนหน้า : 
  <span class="style14">
  <?=$Num_Pages;?>
  </span> 
  หน้า :
  <strong>
  <?
if($Prev_Page)
{
	echo " <a href='$_SERVER[SCRIPT_NAME]?Page=$Prev_Page'><< กลับ</a> ";
}

for($i=1; $i<=$Num_Pages; $i++){
	if($i != $Page)
	{
		echo "[ <a href='$_SERVER[SCRIPT_NAME]?Page=$i'>$i</a> ]";
	}
	else
	{
		echo "<b> $i </b>";
	}
}
if($Page!=$Num_Pages)
{
	echo " <a href ='$_SERVER[SCRIPT_NAME]?Page=$Next_Page'>ถัดไป>></a> ";
}
?>
</div>
</form>

include "config.in.php";

$ProID=$_GET["ProID"] ;
$Project_Name=$_GET["Project_Name"] ;
if($_GET["Action"] == "Update_id")
{
	$strSQL = "UPDATE project SET  Project_Name ='$Project_Name' where Project_ID='$ProID'";
	$objQuery = mysql_query($strSQL);
	if(!$objQuery)

	{
		echo "Error Update [".mysql_error()."]";
	}
                echo "ค่า Action =".$Action."<br>";
                echo "ค่า ID =".$ProID."<br>";
                echo "ค่า Project_Name =".$Project_Name."<br>";
	/*header("location:$_SERVER[PHP_SELF]");
	exit();*/
}