// AJAX - /js/functions.js at the bottom
// Update state of checkboxes (RELAY, LED)
$(function() {
  // for every element state change, code below is executed
  $(document).on("change", ":checkbox", function(){
    // variables holds type and pin, state (0 or 1) and room ID
    name = $(this).attr('name');
    state = (Number(this.checked));
    id_prostor = $(this).attr('title');
    $.ajax({
      type: "POST",
      url: "updateState.php",
      data: { name:name, state:state, id_prostor:id_prostor }
    });
  });
});

// PHP - updateState.php
<?php
include 'connect.php';

$name = $_POST['name'];
$state = $_POST['state'];
$id_prostor = $_POST['id_prostor'];

$stmt = "UPDATE items set state = " . $state . "
where item = '" . $name . "' and id_prostor = " . $id_prostor;

$res = mysqli_query($dbc, $stmt);

?>