Php 上传文件时，我得到了未定义的索引

我在php代码或html中的错误在哪里？我想上传文件.jpeg或.pdf在我的数据库。表单中的所有字段都已保存，但我要上载的文件除外

这是我的php代码

<?php  
if(isset($_POST['new']))  
{  
$host="xxx";//host name  
$username="xxx"; //database username  
$word="";//database word  
$db_name="xxx";//database name  
$tbl_name="doc"; //table name  
$con=mysqli_connect("$host", "$username", "$word","$db_name")or die("cannot connect");//connection string 
$title =$_REQUEST['title'];
$date = $_REQUEST['date'];
$from_to = $_REQUEST['from_to'];
$details = $_REQUEST['details']; 
$d_location = $_REQUEST['d_location'];  
$d_stat = $_REQUEST['d_stat'];  
$upfile = $_REQUEST['upfile'];  
$in_ch=mysqli_query($con,"insert into doc(`title`,`date`,`from_to`,`details`,`d_location`,`d_stat`,`upfile`) values ('$title','$date','$from_to','$details','$d_location','$d_stat','$upfile')");  
if($in_ch==1)  
   {  
      echo'<script>alert("Inserted Successfully")</script>';  
   }  
else  
   {  
      echo'<script>alert("Failed To Insert")</script>';  
   }  
}  

?> 

---

上载的文件存储在
$\u文件中
您必须重新阅读教程。或者，例如，从开始，我得到了数组到字符串的转换。顺便说一句，先生，我稍后再研究
<form action="" method="post" enctype="multipart/form-data">  
<input type="hidden" name="new" value="1" />
<p><input type="text" name="title" placeholder="Fail Title" required />
<input type="date" name="date" placeholder="Date" required /></p>
<p><input type="text" name="from_to" placeholder="From/To by" required /></p>
<p> Details: <br><textarea name="details" required></textarea></p>
<p>Location: <select name="d_location">
  <option value="Local A">Local A</option>
  <option value="local B">Local B</option>
  <option value="local C">Local C</option>
</select></p>
<p>Status: <select name="d_stat">
  <option value="Active">Active</option>
  <option value="Inactive">Inactive</option>
</select></p>
<p>Choose file to upload: <input type="file" name ="upfile" required/></p>
<a href="n_doc.php"><input name="submit" type="submit" value="Create new" /></a>