private function getQuery()
{
$concat = [];
foreach ($this->by as $id) {
$concat[] = "ifnull(`{$id}`,'')";
}
$key = "concat(" . implode(",'-',", $concat) . ") as `__key`";
$columns = implode(",", array_merge([$key], $this->sync));
return $this->builder->selectRaw($columns);
}