insert o tbl(id,dt) values(1,to_char('030508','ddmmrr');

alter session nls_date_format='yyyy-mm-dd hh24:mi:ss';

select substr(to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),1,10) from dual;

alter session nls_date_format='yyyymmdd';

insert o tbl(id,dt) values(2,'20080308');

select * from emp where lower(ename)='king';

select * from emp where ename=upper('king');