what are the three most frequent output event since 2 years ago?
select d_items.label from d_items where d_items.itemid in ( select t1.itemid from ( select outputevents.itemid, dense_rank() over ( order by count(*) desc ) as c1 from outputevents where datetime(outputevents.charttime) >= datetime(current_time,'-2 year') group by outputevents.itemid ) as t1 where t1.c1 <= 3 )