需要从更新更改按钮以保存并同时将文本字段更改为输入字段

Question

我将所有这些代码放在一个文件中：index.php：

<table id="tbl" class = "table table-bordered table-responsive  ">
            <thead>

                <th>Segment</th>

                <th>Action</th>
            </thead>
            <tbody>
            <?php

                require 'class.php';
                $conn = new db_class();
                $read = $conn->read();
                while($fetch = $read->fetch_array()){ 
            ?>
                <tr>

                                        <td><?php echo $fetch['segment']?></td>

                            <form action="activate.php" method="post"> 
                                <input type="hidden" name="id" value="<?php echo $id?>">
                                        <td><center><button class = "btn btn-default" name="update"><a href=""></a><span class = "glyphicon glyphicon-edit"></span> Update</button> | <button class = "btn btn-success" name="activate"><span class = "glyphicon glyphicon-check"></span> Activate</button></center></td>
                            </form>
                </tr>
            <?php
                }
            ?>  
            </tbody>

我需要知道的是如何将更新按钮更改为保存按钮，并将<td>字段更改为输入字段，并进行更改。谢谢大家。