$delete_row = $mysqli->query("UPDATE combats_duty_logs SET duty_time_stop=NOW() , active=0 , duty_time_total=DATEDIFF(duty_time_start, NOW()) WHERE id=".$idToDelete);

$results = $mysqli->query("SELECT * FROM combats_duty_logs WHERE active = 1");
while($row = $results->fetch_assoc())
{
    $previousDate = $row["duty_time_start"];
    $startdate = new DateTime($previousDate);
    $endDate   = new DateTime('now');
    $interval  = $endDate->diff($startdate);
    echo$interval->format('%y years, %m months, %d days');
}

$duty_time_start = $row["duty_time_start"];
$date = new DateTime($duty_time_start);
$now = new DateTime();
echo $date->diff($now)->format("%h:%iмин.");