oracle 两表更新 报错ORA-01779: 无法修改与非键值保存表对应的列

--用B表字段更新A表字段
UPDATE (
select a.is_work iswork from dim_time a ,(select date_num,is_rest
 from WORKTIME_SPECIALDAY@oa ) b where a.fdate = b.date_num and b.IS_REST !=0 --order by a.fdate
)t
set t.iswork =1;

报错:

原因：B表去更新A表字段，在A表和B表关联的时候，B表date_num不是主键或date_num字段没有设置唯一键，导致B表date_num里有重复数据

解决办法：

　　第一种：修改业务数据，使date_num数据唯一

　　第二种：写一个视图(DIM_WORKTIME_SPECIALDAY)，去重之后再更新

select distinct to_date(date_num,'yyyy-mm-dd hh24:mi:ss') as date_num, is_rest
 from WORKTIME_SPECIALDAY where IS_REST =0 and org_account_id ='670869647114347'

UPDATE (
select a.is_work iswork from dim_time a ,(select date_num,is_rest 
 from DIM_WORKTIME_SPECIALDAY ) b where a.fdate = b.date_num and b.IS_REST !=0 order by a.fdate
)t
set t.iswork =1;