How to identify invalid (corrupted) values stored in Oracle DATE columns

This identifies invalid months

SELECT rowid,
       pk_column,
       DUMP(date_column, 1010) AS dump1
FROM   table
WHERE  TO_NUMBER(SUBSTR(DUMP(date_column, 1010), INSTR(DUMP( date_column, 1010),
                                              ',', 1, 2
                                                     ) + 1,
                                  INSTR(DUMP(date_column, 1010), ',', 1, 3) - (
                                  INSTR(DUMP( date_column, 1010), ',', 1, 2) + 1
                                  ))) = 0; 

Update using the same where clause, I found the month number was zero in these cases.

This is a pretty unusual scenario (although I have come across something similar once before). The more common problem is finding invalid dates which are held as strings in a date column. You could adapt the solution for that to your situation, by building your own date validator.

Something like this:

create or replace function is_a_date 
    ( p_date in date )
    return varchar2
is
    d date;
begin
    d := to_date(to_char(p_date,  'SYYYYMMDDHH24MISS'),  'SYYYYMMDDHH24MISS') ;
    if d != p_date then
        return 'not a proper date';
    else
        return 'good date';
    end if;
exception
    when others  then
        return 'not a date';
end;
/ 

This converts a date into a string and back again. It catches exceptions thrown by date casting. If the end product is not the same as the input date then presumably something got lost in translation; to be honest I'm not sure whether the 12011 date would cast successfully to a string, so this is a belt'n'braces approach. It's a bit tricky writing this utility without some test data!

This query would identify all the non-valid dates:

 select h.id, dump(h.bid_close_date)
 from mytable h 
 where h.bid_close_date is not null
 and is_a_date(h.bid_close_date) != 'good date';

Without adding a function, a simple predicate

TO_CHAR(date_col,'YYYYMMDDHH24MISS') = '000000000000'

appears to be satisfactory to identify corrupted values stored in an Oracle DATE column. The addition of a function appears to be unnecessary. Checking for corrupted dates should be able to be done in a SQL SELECT statement, and not require a user to have CREATE FUNCTION privilege on the database.