Oracle数据库，分组排序后取第一条数据

select t.applicant_id, t.organ_id, t.apply_date,t.policy_id
from (select r.applicant_id,
r.organ_id,
r.apply_date,
r.policy_id,
row_number() over(partition by r.applicant_id order by r.apply_date desc) rn
from  t_contract_master r 
) t where t.rn = 1