Courses — PHP and JSON data

Two problems to solve here:

• Producing JSON data on server side
• Processing JSON data on client-side

<?php

/// use Dotenv to load database info  .env file
// DB_HOST, DB_USER, DB_PW, DB_NAME
require_once('vendor/autoload.php');
$dotenv = Dotenv\Dotenv::createImmutable(__DIR__);
$dotenv->safeLoad();

// Connecting, selecting database
$mysqli = new mysqli($_ENV['DB_HOST'],$_ENV['DB_USER'],$_ENV['DB_PW'],$_ENV['DB_NAME']);
if ($mysqli->connect_errno) {
    echo "Failed to connect to mysql: ".$mysqli->connect_errno." ".$mysqli->connect_error;
}

$dept_code = $_GET['department_code'];
$sqlescaped_dept_code = $mysqli->real_escape_string($dept_code);

// Performing SQL query
$query = <<<ENDQUERY
SELECT
  department,
  department_code,
  course_number,
  term,
  academic_year,
  short_title,
  title,
  description,
  faculty_description

  ext_courses
WHERE
  department_code = '$sqlescaped_dept_code'
ORDER BY
  department,
  course_number,
  title
ENDQUERY;

$query_result = $mysqli->query($query);

$i = 0;
while ($row = $query_result->fetch_assoc()) {
  // calculate year
  $academic_year_display = $row['academic_year'];
  if ($row['term'] == 'Spring' or $row['term'] == 'January') {
    $academic_year_display += 1 ;
  }
  $row['academic_year_display'] = $academic_year_display;

  $results[$i++] = $row;
}

$template_data['courses'] = $results;
$template_data['department_name'] = $dept_code;

header('Content-type: application/json');
echo json_encode($template_data);

// cleanup query result and close connection
$query_result->free();
$mysqli->close();
?>