JUST DO IT ~

select multi_result  -1
from
(
select
 dbms_aw.eval_number(   replace(wmsys.wm_concat(result )over(order by rownum), ',', '*')  )  multi_result
from
(select date_ ,
       value ,
       case
         when rownum1 = icount then
         4* value
         else
          1* value
       end   result
  from (select a.date_ , a.value, a.rownum1, b.icount
          from (select date_, value , rownum rownum1
                  from (select date_, value  from a2 order by date_ )) a, --確保順序
               (select count(*) icount from a2 order by date_   ) b --確保順序
        )
)
order by rownum  desc
)
where rownum < 2

select    wmsys.wm_concat(a )over(order by rownum) , replace(wmsys.wm_concat(a )over(order by rownum), ',', '*'),
  dbms_aw.eval_number(   replace(wmsys.wm_concat(a )over(order by rownum), ',', '*')  ) serial_multi
from  a2

drop table a2 ;
create table  a2 (
date_  date ,
value    number
)

select * from a2
 for update
 
 
select * from a2
order by   date_

 for update