
select * from (
select first_name, 
       last_name, 
       salary, 
       nvl(versions_starttime, to_date( '1', 'YYYY')) as start_time, 
       nvl(versions_endtime, sysdate) as end_time 
       from accountants versions between scn minvalue and maxvalue
)
where 
start_time < to_date('20071119-2000', 'YYYYMMDD-hh24mi')
order by start_time