ohctech_p8/select_grade.php

<?php
include('includes/config/config.php');
$gradeId = $_REQUEST['gradeId'];
$query = "select * from grade_master where grade_id = '" . $gradeId . "' ";
if (!$result = @mysqli_query($conn, $query)) {
  die(mysqli_error($conn));
}
$data = array();
if (mysqli_num_rows($result) > 0) {
  while ($row = mysqli_fetch_assoc($result)) {
    $data = $row;
  }
} else {
  $data['status'] = 200;
  $data['message'] = "Data not found!";
}
echo json_encode($data);