delete_files.php
$dir = "uploadfiles";//设置文件保存目录 注意包含/
   $id=$_GET['delete'];
    $conn=mysql_connect('localhost','root','');
    $flag=mysql_select_db('laborder' ,$conn);
    mysql_query("set names utf8");
    $sql="select * from files where files_id='$id'";
    $sqlupdate="delete from student where student_id='$id'";
     $result=mysql_query($sql,$conn);
         if($lists=mysql_fetch_array($result))
         { $name=$lists['files_name'];
           $a=dirname(__FILE__);
           $i=unlink($a/$dir/$name);
                  if(mysql_query($sqlupdate)&&$i)
                  {   
                      
                       echo" <script type='text/javascript'>"
                      ."txtOption='删除成功!';".
                      "alert(txtOption);";
                       echo "</script>";  
                       echo "<script>window.location.href='admin_files.php';</script>";
                       
                  }
         }

$xxx = "{$a}/{$dir}/{$name}";
echo $xxx;
unlink($xxx);

------解决方案--------------------
路径要对，权限要有，必须是个文件

------解决方案--------------------

探讨

E:\work\wamp\www\test5/uploadfiles/SOBEL算子.doc}
 按照3楼的更改居然有这个警告