Error with placing Combobox in HTML form using PHP

I answered you. You have to simply change the code like this -

Change <form></form> code -
 

form></form> code - 

<form action="" method="post" name="form1">
        <table width="25%" border="0">
            <tr>
                <td>RollNo</td>
                <td><input type="number" min = 1  name="RollNo"></td>
            </tr>
<tr><td> 
<?php 
$cser=mysqli_connect("localhost","root","","test") or die("connection failed:".mysqli_error());
$result = mysqli_query($cser,"SELECT pname FROM crud2") or die(mysql_error());
if (mysqli_num_rows($result)!=0)
{
echo 'Subject Name : </td><td><select name="pname">
      <option value=" " selected="selected">Choose one</option>';
   while($drop_2 = mysqli_fetch_array( $result ))
{
  echo '<option value="'.$drop_2['pname'].'">'.$drop_2['pname'].'</option>';
}
echo '</select>';
}
?>
</td>
</tr> 
            <tr>
                <td>Name</td>
                <td><input type="text" pattern="[a-zA-Z][a-zA-Z ]{2,}"  name="Name"></td>
            </tr>
            <tr>
                <td>ObtainedMarks</td>
                <td><input type="number" min = 1 name="ObtainedMarks"></td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" name="Submit" value="Enter"></td>
            </tr>
        </table>
    </form>

Change the PHP database name, column name.

This is form code.  Search form code inside the insert code and replace complete form code to this.