alter table tenant_employees add column last_sync_time datetime;
alter table tenant_users add column last_sync_time datetime;
update tenant_users set last_updated_time=created_time where last_updated_time is null;
update tenant_employees set last_updated_time=created_time where last_updated_time is null;
update tenant_users set last_sync_time=last_updated_time where last_sync_time is null;
update tenant_employees set last_sync_time=last_updated_time where last_sync_time is null;