Fire a specific SQL Query depending on the dropbox at the same page made using Bootstrap

Well, I have a bootstrap Dropbox on this page and depending on the value selected I need to fire the SQL Query and only list down students of that particular batch.

//THE DROPBOX CODE

       <tr>
                        <td>
                          <h5>'.$subject_name[$i].'</h5>
                        </td>
                        <td>0</td>
                        <td>
                          <div class="dropdown">
                            <a class="dropdown-toggle" data-toggle="dropdown">
                            <span id="'.$j.'" class="abc">Theory</span>
                            <span class="caret"></span></a>
                            <ul class="dropdown-menu '.$j.'"" onclick="drop(event);">
                              <li select value="theory"><a href="#">Theory</a></li>
                              <li class="divider"></li>
                              <li value="Practical A"><a href="#">Practical - A</a></li>
                              <li value="Practical B"><a href="#">Practical - B</a></li>
                              <li value="Practical C"><a href="#">Practical - C</a></li>
                              <li class="divider"></li>
                              <li value="Elective PCD"><a href="#">Electives - PCD</a></li>
                              <li value="Elective OR"><a href="#">Electives - OR</a></li>
                              <li value="Elective HCI"><a href="#">Electives - HCI</a></li>
                            </ul>
                          </div>
                            <script>
                                $(".'.$j.' a").click(function(){
                                 $("#'.$j.'").text($(this).text());
                                 });
                            </script>
                              </td>
                              <td>
                                <button type="button" class="btn btn-primary btn-sm" data-toggle="modal" data-target="#myModal">
                                  Mark attendance
                                </button>
                              </td>
                            </tr>

//THE PHP CODE

http://ift.tt/2k9DF2K