private function PublishedCondition()
    {
        $sql = Access::SqlBuilder();
        $sqlNow = $sql->Value(Date::Now());
        $tblArticle = Article::Schema()->Table();
        return $sql->Equals($tblArticle->Field('Publish'), $sql->Value(true))
                    ->And_($sql->IsNull($tblArticle->Field('PublishFrom'))
                        ->Or_($sql->LTE($tblArticle->Field('PublishFrom'), $sqlNow)))
                    ->And_($sql->IsNull($tblArticle->Field('PublishTo'))
                        ->Or_($sql->GTE($tblArticle->Field('PublishTo'), $sqlNow)));
    }