SQL> with
  2   data as (
  3     select  '09/09/2015' v from dual
  4     union all
  5     select '2016-04-28' from dual
  6   )
  7  select v, regexp_replace(v, '(\d{2})/(\d{2})/(\d{4})', '\3-\2-\1') new_v
  8  from data
  9  /
V          NEW_V
---------- ----------
09/09/2015 2015-09-09
2016-04-28 2016-04-28

2 rows selected.

  1  with
  2     data as (
  3       select  '09/09/2015' v from dual
  4       union all
  5       select '2016-04-28' from dual)
  6  select to_date(v,'MM/DD/YYYY')
  7  FROM DATA
  8  WHERE INSTR(V,'/') > 0
  9  UNION ALL
 10  SELECT TO_DATE(V,'YYYY-MM-DD')
 11  FROM DATA
 12  WHERE INSTR(V,'-') > 0
 13* ORDER BY 1
 14  /

TO_DATE(V
---------
09-SEP-2015
28-APR-2016

DECLARE
  CURSOR CUR_DATE_VAL 
  IS
  SELECT (year_val||'-'||month_val||'-'||date_val)dateval,
  	    id 
     FROM ( SELECT lastupdate,id,
                   substr(substr(lastupdate,instr(lastupdate,'/',-2)+1),1,4)year_val,
                   substr(lastupdate,1,instr(lastupdate,'/',1)-1) month_val,
                   substr(lastupdate,instr(lastupdate,'/',1)+1,(instr(lastupdate,'/',1,2)-instr(lastupdate,'/',1))-1)date_val
              FROM sap_products_country_test)
             WHERE month_val IS NOT NULL
               AND date_val IS NOT NULL;

    TYPE date_val_tab IS TABLE OF cur_date_val%ROWTYPE;
    l_date_val_tab         date_val_tab;   
    
BEGIN
   OPEN  cur_date_val;
   FETCH cur_date_val BULK COLLECT INTO l_date_val_tab LIMIT 1000;
   CLOSE cur_date_val;
   IF l_date_val_tab.COUNT > 0 
   THEN
      FOR i in l_date_val_tab.FIRST..l_date_val_tab.LAST
      LOOP
         UPDATE sap_products_country_test
            SET lastupdate = l_date_val_tab(i).dateval
          WHERE id = l_date_val_tab(i).id;
      END LOOP;
   END IF;  
	
EXCEPTION
   WHEN OTHERS 
   THEN 
      RAISE_APPLICATION_ERROR(-20001,SQLERRM);
END;

CREATE TABLE date_test(dateval varchar2(20),id number);
insert into date_test(dateval) values('05/05/2016',1);
insert into date_test(dateval) values('2016-05-04',2);
insert into date_test(dateval) values('4/30/2016',3);
insert into date_test(dateval) values('2/21/2012',4);
insert into date_test(dateval) values('1/13/2015',5);
insert into date_test(dateval) values('1/12/2016',6);
insert into date_test(dateval) values('7/9/2013',7);
insert into date_test(dateval) values('2011-11-29',8);
insert into date_test (dateval)values('2014-11-25',9);
insert into date_test (dateval) values('2014-11-18',10);
insert into date_test(dateval) values('3/10/2015',11);
declare
cursor cur_date_val is
select (year_val||'-'||month_val||'-'||date_val)dateval,
       month_val,
       date_val,
       id 
                 from ( select dateval,id,
                               substr(substr(dateval,instr(dateval,'/',-2)+1),1,4)year_val,
                               substr(dateval,1,instr(dateval,'/',1)-1) month_val,
                               substr(dateval,instr(dateval,'/',1)+1,(instr(dateval,'/',1,2)-instr(dateval,'/',1))-1)date_val
                          from date_test)
                where month_val is not null
                  and date_val is not null;

    TYPE date_val_tab IS TABLE OF cur_date_val%ROWTYPE;
    l_date_val_tab         date_val_tab;   
    
begin
  OPEN   cur_date_val;
  FETCH cur_date_val BULK COLLECT INTO l_date_val_tab;
  CLOSE cur_date_val;
  IF l_date_val_tab.COUNT > 0 
  THEN
    FOR i in l_date_val_tab.FIRST..l_date_val_tab.LAST
    LOOP
      dbms_output.put_line('Date Value: '||l_date_val_tab(i).dateval);
      update date_test
         set dateval = l_date_val_tab(i).dateval
       where id = l_date_val_tab(i).id;
        
    END LOOP;
  END IF;  
exception
when others then 
raise_application_error(-20001,sqlerrm);
end;