public function ensureChangedFlagsAreSet(SiteHistoryModel $sitehistory)
 {
     global $DB;
     // do we already have them?
     if (!$sitehistory->isAnyChangeFlagsUnknown()) {
         return;
     }
     // load last.
     $stat = $DB->prepare("SELECT * FROM site_history WHERE site_id = :id AND created_at < :at " . "ORDER BY created_at DESC");
     $stat->execute(array('id' => $sitehistory->getId(), 'at' => $sitehistory->getCreatedAt()->format("Y-m-d H:i:s")));
     if ($stat->rowCount() == 0) {
         $sitehistory->setChangedFlagsFromNothing();
     } else {
         while ($sitehistory->isAnyChangeFlagsUnknown() && ($lastHistoryData = $stat->fetch())) {
             $lastHistory = new SiteHistoryModel();
             $lastHistory->setFromDataBaseRow($lastHistoryData);
             $sitehistory->setChangedFlagsFromLast($lastHistory);
         }
     }
     // Save back to DB
     $sqlFields = array();
     $sqlParams = array('id' => $sitehistory->getId(), 'created_at' => $sitehistory->getCreatedAt()->format("Y-m-d H:i:s"), 'is_new' => $sitehistory->getIsNew() ? 1 : 0);
     if ($sitehistory->getTitleChangedKnown()) {
         $sqlFields[] = " title_changed = :title_changed ";
         $sqlParams['title_changed'] = $sitehistory->getTitleChanged() ? 1 : -1;
     }
     if ($sitehistory->getSlugChangedKnown()) {
         $sqlFields[] = " slug_changed = :slug_changed ";
         $sqlParams['slug_changed'] = $sitehistory->getSlugChanged() ? 1 : -1;
     }
     if ($sitehistory->getDescriptionTextChangedKnown()) {
         $sqlFields[] = " description_text_changed = :description_text_changed ";
         $sqlParams['description_text_changed'] = $sitehistory->getDescriptionTextChanged() ? 1 : -1;
     }
     if ($sitehistory->getFooterTextChangedKnown()) {
         $sqlFields[] = " footer_text_changed = :footer_text_changed ";
         $sqlParams['footer_text_changed'] = $sitehistory->getFooterTextChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsWebRobotsAllowedChangedKnown()) {
         $sqlFields[] = " is_web_robots_allowed_changed = :is_web_robots_allowed_changed ";
         $sqlParams['is_web_robots_allowed_changed'] = $sitehistory->getIsWebRobotsAllowedChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsClosedBySysAdminChangedKnown()) {
         $sqlFields[] = " is_closed_by_sys_admin_changed = :is_closed_by_sys_admin_changed ";
         $sqlParams['is_closed_by_sys_admin_changed'] = $sitehistory->getIsClosedBySysAdminChanged() ? 1 : -1;
     }
     if ($sitehistory->getClosedBySyAdminReasonChangedKnown()) {
         $sqlFields[] = " closed_by_sys_admin_reason_changed = :closed_by_sys_admin_reason_changed ";
         $sqlParams['closed_by_sys_admin_reason_changed'] = $sitehistory->getClosedBySyAdminReasonChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsListedInIndexChangedKnown()) {
         $sqlFields[] = " is_listed_in_index_changed = :is_listed_in_index_changed ";
         $sqlParams['is_listed_in_index_changed'] = $sitehistory->getIsListedInIndexChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureImporterChangedKnown()) {
         $sqlFields[] = " is_feature_importer_changed = :is_feature_importer_changed ";
         $sqlParams['is_feature_importer_changed'] = $sitehistory->getIsFeatureImporterChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureCuratedListChangedKnown()) {
         $sqlFields[] = " is_feature_curated_list_changed = :is_feature_curated_list_changed ";
         $sqlParams['is_feature_curated_list_changed'] = $sitehistory->getIsFeatureCuratedListChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureMapChangedKnown()) {
         $sqlFields[] = " is_feature_map_changed = :is_feature_map_changed ";
         $sqlParams['is_feature_map_changed'] = $sitehistory->getIsFeatureMapChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureVirtualEventsChangedKnown()) {
         $sqlFields[] = " is_feature_virtual_events_changed = :is_feature_virtual_events_changed ";
         $sqlParams['is_feature_virtual_events_changed'] = $sitehistory->getIsFeatureVirtualEventsChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeaturePhysicalEventsChangedKnown()) {
         $sqlFields[] = " is_feature_physical_events_changed = :is_feature_physical_events_changed ";
         $sqlParams['is_feature_physical_events_changed'] = $sitehistory->getIsFeaturePhysicalEventsChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureGroupChangedKnown()) {
         $sqlFields[] = " is_feature_group_changed = :is_feature_group_changed ";
         $sqlParams['is_feature_group_changed'] = $sitehistory->getIsFeatureGroupChanged() ? 1 : -1;
     }
     if ($sitehistory->getPromptEmailsDaysInAdvanceChangedKnown()) {
         $sqlFields[] = " prompt_emails_days_in_advance_changed = :prompt_emails_days_in_advance_changed ";
         $sqlParams['prompt_emails_days_in_advance_changed'] = $sitehistory->getPromptEmailsDaysInAdvanceChanged() ? 1 : -1;
     }
     if ($sitehistory->getIsFeatureTagChangedKnown()) {
         $sqlFields[] = " is_feature_tag_changed = :is_feature_tag_changed ";
         $sqlParams['is_feature_tag_changed'] = $sitehistory->getIsFeatureTagChanged() ? 1 : -1;
     }
     $statUpdate = $DB->prepare("UPDATE site_history SET " . " is_new = :is_new, " . implode(" , ", $sqlFields) . " WHERE site_id = :id AND created_at = :created_at");
     $statUpdate->execute($sqlParams);
 }