update ht_wcs2_pol t
set t.result = '8'
where t.result = '3'
and exists (
select 1
from ht_wcs2_pol_res2 t2,
ocp_policy_versions t3
where t2.contract_id = t.contract_id
and t2.contract_id = t3.contract_id
and t2.version_no = t3.version_no
and t3.business_start_date >= t.change_date
);
There is another table named "t2".
If you expand select list with ", t2." or where clause with "and t2.", code assistant show columns of table t2.