postgresql7.1 select to_char(start_date, 'YYYY-MM-DD HH24:MI:SS') as ansi_start_date, to_char(end_date, 'YYYY-MM-DD HH24:MI:SS') as ansi_end_date, to_char(now(), 'YYYY-MM-DD HH24:MI:SS') as ansi_today, coalesce(e.name, a.name) as name, coalesce(e.status_summary, a.status_summary) as status_summary, e.event_id as item_id, recurrence_id, (select type from cal_item_types where item_type_id= ci.item_type_id) as item_type, cals.calendar_id, cals.calendar_name from acs_activities a, acs_events e, timespans s, time_intervals t, cal_items ci, calendars cals where e.timespan_id = s.timespan_id and s.interval_id = t.interval_id and e.activity_id = a.activity_id and ci.cal_item_id= e.event_id and (start_date > to_date(:start_date,:date_format) or :start_date is null) and (start_date < to_date(:end_date,:date_format) or :end_date is null) and cals.calendar_id = ci.on_which_calendar $calendars_clause order by $sort_by