select * from (
select
snp.begin_interval_time beg,
snp.end_interval_time end,
par.value,
lag(par.value) over (order by par.snap_id) prev_value,
par.isdefault,
par.ismodified
from
dba_hist_parameter par join
dba_hist_snapshot snp on par.snap_id = snp.snap_id
where
par.parameter_name = 'cursor_sharing'
order by
par.snap_id desc
)
where
value != prev_value;