php-mysql数据从数据库输入到联系人表单

我需要在联系人表单的隐藏字段中放入一些预定义的文本，然后将其发送到邮件中。但它没有在邮件中显示。有什么帮助吗？我的表单代码是：

<?php 
require('assets/dbconn.php');
$result = mysqli_query($con,"SELECT * FROM auctions WHERE id=$id");
$row = mysqli_fetch_array($result);
?>
<form  class="form" id="contactForm" method="post" enctype="multipart/form-data"  action='action.php'>
<label for="email" class="label_text">E-mail:<span class="required_sign">*</span></label>
<input id="email" name="email" class="required" type="email" />
<input type="hidden" name="code" value="<?php echo $row['CodeFromDB']; ?>" />
<button type="submit">SEND</button>
</form>