left join affect other php - php

Question

Hi I wanted to show port_name instead of port ID ($row['port_name']) so I made this query.
$stmt = $db->prepare("SELECT * FROM reservations
INNER JOIN ports ON reservations.port=ports.id WHERE NOT
((end <= :start) OR (start >= :end))");
$stmt->bindParam(':start', $_POST['start']);
$stmt->bindParam(':end', $_POST['end']);
$stmt->execute();
$result = $stmt->fetchAll();
class Event {}
$events = array();
date_default_timezone_set("UTC");
$now = new DateTime("now");
$today = $now->setTime(0, 0, 0);
foreach($result as $row) {
$e = new Event();
$e->id = $row['id'];
$e->service_id = $row['service_id'].'<br/>';
$e->service_classification = $row['service_classification'].'<br/>';
$e->text = $row['port_name'].'<br/>';
$e->start = $row['start'];
$e->end = $row['end'];
$e->resource = $row['room_id'];
$e->customer = $row['customer'];
$events[] = $e;
}
header('Content-Type: application/json');
echo json_encode($events);
?>
It is working and showing me port names like it should, but when I want to move with event or resize my event (I have calendar of "events") and then I refresh page events stay on previous positions. When I delete JOIN and leave there port_id (reservations.port) everything is working!
resize.php:
class Result {}
$stmt = $db->prepare("UPDATE reservations SET start = :start, end = :end WHERE id = :id");
$stmt->bindParam(':id', $_POST['id']);
$stmt->bindParam(':start', $_POST['newStart']);
$stmt->bindParam(':end', $_POST['newEnd']);
$stmt->execute();
$response = new Result();
$response->result = 'OK';
$response->message = 'Update successful';
header('Content-Type: application/json');
echo json_encode($response);
I don't get it, because I only update new start and end date. Any ideas? Thanks