<form  id="addForm"  enctype='multipart/form-data'>
<input type=hidden name='action' value='add'>
Имя:<input type=text name="name"><br><br>
Возраст:<input type=text name="age"><br><br>
Баллы:<input type=text name="points"><br><br>
Город:<input type=text name="city"><br><br>
<input type=file name="file" accept="image/*"><br><br>
<input type=submit value="Добавить студента">

if (isset($_POST['action']) && $_POST['action']=='add')
{

if (isset($_REQUEST['name'])) $name=$_REQUEST['name'];
if (isset($_REQUEST['age'])) $age=$_REQUEST['age'];
if (isset($_REQUEST['points'])) $points=$_REQUEST['points'];
if (isset($_REQUEST['city'])) $city=$_REQUEST['city'];