html后台修改和添加数据判断

<div class="box box2">
<notempty name="msg">
<form action="{:U('Message/add_msg')}" method="post">
<else />
<form action="{:U('Message/add_msg')}" method="post">
</notempty>
<div class="product">
<div class="show">
{:isset($msg['n_id'])?'<h1>修改信息栏目类型</h1>':'<h1 class="boxh1">添加信息栏目类型</h1>'}
<select name="n_type" id="">
<option value="{$msg['n_type']}" <?php if($msg['n_type']=='0'){echo 'selected';} ?>>系统公告</option>
<option value="{$msg['n_type']}" <?php if($msg['n_type']=='1'){echo 'selected';} ?>>公司新闻</option>
<option value="{$msg['n_type']}" <?php if($msg['n_type']=='2'){echo 'selected';} ?>>公司视频</option>
<option value="{$msg['n_type']}" <?php if($msg['n_type']=='3'){echo 'selected';} ?>>案例视频</option>
<option value="{$msg['n_type']}" <?php if($msg['n_type']=='4'){echo 'selected';} ?>>教学视频</option>
</select>
</div>
<div class="show">
<h1>内容标题</h1>
<input type="text" name="n_title" value="{$msg.n_title}">
</div>
<div class="show">
<h1>文章内容</h1>
<textarea type="text/plain" name="n_content" style="width:100%;height:100px;" >{$msg.n_content}</textarea>
<!--<img class="lazyload" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC" data-original="PUBLIC/admin/images/10.jpg" alt="" value="{$msg['n_content']}">-->
</div>
</div>
<div class="save">
<notempty name="msg['n_id']">
<input type="hidden" name="n_id" value="{$msg.n_id}"/>
</notempty>
<input type="submit" value="保存">
<a href="javascript:history.go(-1)">取消</a>
</div>
</form>