oracle8.1.7 SELECT percent_score, to_char(creation_datetime, :format) AS session_start, to_char(completed_datetime, :format) AS session_finish, round ((completed_datetime - creation_datetime)* 1440 ) as session_time FROM as_sessions s WHERE s.session_id = :session_id select * from (select max(o.creation_date), s.session_id from as_sessions s, acs_objects o, cr_revisions cr where s.subject_id=:user_id and s.assessment_id in (select revision_id from cr_revisions where item_id= :assessment_id) and o.object_id = cr.item_id and s.session_id = cr.revision_id group by assessment_id, subject_id, session_id) order by o.creation_date desc where rownum=1