使用PHP更新单个MYSQL记录

我正在尝试向当前显示MYSQL表内容的表添加编辑功能。

我可以添加和删除记录，但是似乎无法对其进行编辑。

下面是我的代码。谁能告诉我我在做什么错？

//Editing a record


    $name=$_POST['editc'];
    $sql="UPDATE course SET name='$name' WHERE id='$id'";
    $result=mysql_query($sql);

// if successfully updated.
    if($result)
    {
        echo "Successful";
        echo "<BR>";
    }
    else 
    {
        echo "ERROR";
    }

  echo'
        <form action"'.$_SERVER['PHP_SELF'].'" method="POST">
            <table border="1" width="80%" align="center"> 
                <tr>
                    <td>
                        <h4>Record ID</h4>
                    </td>
                    <td>
                        <h4>Record Name</h4>
                    </td>
                    <td>
                        <h4>Add/Edit Record</h4>
                    </td>
                    <td>
                        <h4>Remove Selected Record(s)</h4>
                    </td>
                </tr>
                <tr>
                    <td>
                        <h5>Create New Record</h5>
                    </td>
                    <td>
                        <input type="text" name="cname" value="Type New Record Name Here" size="50"/>
                    </td>
                    <td>
                        <input type="Submit" name="Add" value="Add Record"/>
                    </td>
                    <td>
                        <h5> Select items you wish to remove, then click "Delete Selected" </h5>
                    </td>
                </tr>
                ';
                    while ($row=mysql_fetch_array($query))
                        {
                            echo'<tr>
                                    <td>
                                        '.$row['cid'].'
                                    </td>
                                    <td>
                                        '.$row['cname'].'
                                    </td>
                                    <td align="center">
                                        <input type="text" name="editc" value="Modify record Name">
                                        <input type="submit" name="cedit"   value="Edit" />

                                    </td>
                                    <td align="center">
                                        <input type="checkbox" name="cid[]" value="'.$row['cid'].'"/>
                                    </td>
                                </tr>';
                        }

            mysql_free_result($query);

            echo '

            </table>
            <br/>
            <br/>

            <div align = "center">
                <input type="submit" name="deletesel" value="Delete Selected"/>
                ---
                <input type="reset" name="unselect" value="Deselect All"/>
            </div>
        </form>

    ';