MySQL UPDATE给出了错误

I have tried for hours now to update a MySQL table with PHP.

I used the following code (and several others) but it gives an error message:

    $id = $_GET['id'];

    if(isset($_POST['descr'])){
    $go = $_POST['descr'];

    mysql_query("UPDATE Rooms SET Desc='$go' WHERE Room_ID='$id'") 
    or die(mysql_error());  

    }


    mysql_close($conn);

with the error: "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Desc='This room is the primary test-room. It is?' WHERE Room_ID='11'' at line 1"

The form is called: "descr", the table "Rooms", the field that needs update is "Desc" and it should be where the corresponding ID is, based on a dynamic URL.

If I write echo = $go it outputs the correct data, so I suppose it's the php.

It DOES connect correctly to the database.

Desc is a special word in mysql try it by escape

 mysql_query("UPDATE Rooms SET `Desc`='$go' WHERE Room_ID='$id'")

Assuming that ID is a number:

$id = $_GET['id'];

if(isset($_POST['descr'])){
$go = $_POST['descr'];

mysql_query("UPDATE Rooms SET `Desc`='".$go."' WHERE Room_ID=".$id.") 
or die(mysql_error());  
}
mysql_close($conn);

Desc is reserved for ORDER BY! Enclose it with '`' symbols!

mysql_query("UPDATE `Rooms` SET `Desc` = '".$go."' WHERE `Room_ID` = ".$id.") 
or die(mysql_error());