maxim_01

$updatingFields = [];

foreach (['name', 'familia'] as $field) {
    if (isset($_POST[$field]) && $fieldValue = trim($_POST[$field])) {
        $updatingFields[] = sprintf("%s = '%s'", $field, $link->real_escape_string($fieldValue));
    }
}

$result = null;
if (count($updatingFields)) {
    $query = sprintf(
        "
            UPDATE users
            SET %s
            WHERE id = '%s'
        ",
        implode(', ', $updatingFields),
        $link->real_escape_string($id)
    );

    $result = $link->query($query);
}