private static function getMultiOrderBy(GDO $gdo, $user)
{
$fields = $gdo->getSortableFields($user);
# Gather the current selected sorting
$curBy = explode(',', Common::getGetString('by', ''));
$curDir = explode(',', Common::getGetString('dir', ''));
$back = '';
foreach ($curBy as $i => $cby) {
if (in_array($cby, $fields, true)) {
$cd = isset($curDir[$i]) ? $curDir[$i] : 'ASC';
$cd = GDO::getWhitelistedDirS($cd, 'ASC');
$back .= sprintf(',`%s` %s', $cby, $cd);
}
}
return $back === '' ? '1' : substr($back, 1);
}
