select email 
from member 
where regexp_like(email,'[^ ]+@[^.][^ ]+\..[^ ]+');

'[a-zA-Z0-9._%-]+@[a-zA-Z0-9._%-]+\.[a-zA-Z]{2,4}' 

http://stackoverflow.com/questions/787167/validation-on-email-postcode-fields-in-sql-oracle

ALTER SESSION SET NLS_LANGUAGE='AMERICAN';
with t as (
  select '01-02-2007' str from dual union all
  select '7-8-2007'   str from dual union all
  select '2007/03/28' str from dual union all
  select '10-MAY-07'  str from dual
)
select str
  , to_date(str, case when regexp_like(str,'[0-9]{1,2}-[0-9]{1,2}-[0-9]{4}')
                           then 'dd-mm-yyyy'
                      when regexp_like(str,'[0-9]{4}/[0-9]{1,2}/[0-9]{1,2}')
                           then 'yyyy/mm/dd'
                      when regexp_like(str,'[0-9]{2}-[A-Z]{3}-[0-9]{2}')
                           then 'dd-mon-yy'
                 end) as date1
from t;

ORA-01843: not a valid month 가 나올경우 NLS_LANG 을 확인해 본다.

with t as (
  select '01-02-2007' str from dual union all
  select '7-8-2007'   str from dual union all
  select '2007/03/28' str from dual union all
  select '10-MAY-07'  str from dual
)
select str
  , to_date(str, case when regexp_like(str,'[0-9]{1,2}-[0-9]{1,2}-[0-9]{4}')
                           then 'dd-mm-yyyy'
                      when regexp_like(str,'[0-9]{4}/[0-9]{1,2}/[0-9]{1,2}')
                           then 'yyyy/mm/dd'
                      when regexp_like(str,'[0-9]{2}-[A-Z]{3}-[0-9]{2}')
                           then 'dd-mon-yy'
                 end,'NLS_DATE_LANGUAGE=AMERICAN') as date1
from t;