getting error
Notice: Undefined index: device_id in C:\xampp\htdocs\Real-Time-master\server\gps-2-map\api\index.php on line 17
Notice: Undefined index: date_and_time in C:\xampp\htdocs\Real-Time-master\server\gps-2-map\api\index.php on line 18
Notice: Undefined index: latitude in C:\xampp\htdocs\Real-Time-master\server\gps-2-map\api\index.php on line 19
Notice: Undefined index: longitude in C:\xampp\htdocs\Real-Time-master\server\gps-2-map\api\index.php on line 20
// Establish a connection to database
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '');
define('DB_DATABASE', 'gps2db');
$db_connection = mysqli_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD,DB_DATABASE);
// Extract POST-data to variables
$device_id = mysqli_real_escape_string($db_connection, $_POST['device_id']);
$date_and_time = mysqli_real_escape_string($db_connection, $_POST['date_and_time']);
$latitude = mysqli_real_escape_string($db_connection, $_POST['latitude']);
$longitude = mysqli_real_escape_string($db_connection, $_POST['longitude']);
// Validate URL - If required parameters are found, continue processing
if(isset($device_id) && isset($date_and_time) && isset($latitude) && isset($longitude))
{
// Check that device corresponding to device_id aka MAC-address is found from database
$check_device = mysqli_query($db_connection,"SELECT device_id FROM devices WHERE device_id = '$device_id'");
// If device corresponding to device_id is found, continue processing
if(mysqli_num_rows($check_device))
{
// Find out if there is any existing location information in database for given device