似乎无法通过id编辑/修改我的php表

<?php
$con = mysql_connect("localhost","root");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }


mysql_select_db("database", $con);

if(!isset($_POST['submit'])){
$result = mysql_query("SELECT * FROM pleasework ORDER BY ID"); 
$row = mysql_fetch_array($result);
}

?>

<form action="?php echo $_SERVER['PHP_SELF'];?>" id="form2" method="post" name="form2">
<img id="close1" src="X.png" width="25" height="25" onclick ="div_hide1()">
<h2><font size="6">Please change existing data</font></h2>
<hr>
<br> 

     <font color="yellow">Change Name to: </font><input type="text" name="New" value="<?php echo $row['Name'];?>"/><br><br>
      <font color="yellow"> Change Cause to: </font> <input type="text" name="New1" value="<?php echo $row['Cause'];?>"/><br><br>
     <font color="yellow">Change Symptom to:  </font><input type="text" name="New2" value="<?php echo $row['Symptom'];?>"/><br><br>
      <font color="yellow"> Change Gene_affected to:  </font><input type="text" name="New3"value="<?php echo $row['Gene_affected'];?>" /><br><br>
      <input type="hidden" name="id" value="<?php echo $_GET['ID'];?>"/>
    <input type="submit" onclick="clicked(event)" />
</form>

<?php
if(isset($_POST['submit'])){
mysql_query("UPDATE pleasework SET Name= '$_POST[New]' WHERE ID='$_POST[id]'");
mysql_query("UPDATE pleasework SET Cause= '$_POST[New1]' WHERE     ID='$_POST[id]'");
mysql_query("UPDATE pleasework SET Symptom= '$_POST[New2]' WHERE ID='$_POST[id]'");
mysql_query("UPDATE pleasework SET Gene_affected= '$_POST[New3]' WHERE ID='$_POST[id]'");
echo "Change Successful<br>" ;
header("Location: databse.php");
mysql_close($con);
} 
else {}
?>
<?php
$con = mysql_connect("localhost","root");