Oracle specific timestamp format 'DD-MON-RR HH.MI.SSXFF AM'

Question

I have a problem with Oracle 11g specific timestamp format.

This is what I have: select to_timestamp('21-OCT-15 08.24.30.000000000 PM','DD-MON-RR HH.MI.SSXFF AM') from dual;

Response from database: ORA-01855: AM/A.M. or PM/P.M. required 01855. 00000 - "AM/A.M. or PM/P.M. required"

I have also tried to alter session settings with several commands and still nothing.

alter session set NLS_LANGUAGE='ENGLISH';
alter session set NLS_DATE_LANGUAGE='ENGLISH';
alter session set NLS_TIMESTAMP_FORMAT = 'DD-MON-RR HH.MI.SSXFF AM';
alter session set NLS_TIMESTAMP_TZ_FORMAT='DD-MON-RR HH.MI.SSXFF AM';

I can't change timestamp format in SELECT statement, need to stay as it is. I guess the issue is in session settings.

Someone experienced in oracle database administration can suggest something, I will try. I know there are a couple of similar posts but I didn't find a solution. Thanks

Here are my session settings.

select * from nls_session_parameters;

Answer 1

The core problem is that, on the session level, you have nls_numeric_characters=',.' while your timestamp string contains dot (.) as the seconds-from-microseconds delimiter instead.

The to_timestamp() function can accept a third parameter for overrides of the NLS settings. Here's a small demo for you ...

Connected to Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 
Connected as ******@******

--- This is how it behaves in your database (with "," as the decimals separator) ...

SQL> alter session set nls_numeric_characters = ',.';

Session altered

SQL> select to_timestamp('21-OCT-15 08.24.30.000000000 PM','DD-MON-RR HH.MI.SSXFF AM') as xx from dual;

select to_timestamp('21-OCT-15 08.24.30.000000000 PM','DD-MON-RR HH.MI.SSXFF AM') as xx from dual

ORA-01855: AM/A.M. or PM/P.M. required

--- This is how it behaves in my database (with "." as the decimals separator) ...

SQL> alter session set nls_numeric_characters = '. ';

Session altered

SQL> select to_timestamp('21-OCT-15 08.24.30.000000000 PM','DD-MON-RR HH.MI.SSXFF AM') as xx from dual;

XX
-------------------------------------------------
21.10.15 20:24:30.000000000

--- Now back to your database settings and let's make the conversion NLS-settings-indepenent ...

SQL> alter session set nls_numeric_characters = ',.';

Session altered

SQL> select to_timestamp('21-OCT-15 08.24.30.000000000 PM','DD-MON-RR HH.MI.SSXFF AM', 'nls_numeric_characters = ''. ''') as xx from dual;

XX
-------------------------------------------------
21.10.15 20:24:30,000000000

SQL> 

Please notice the third parameter to the to_timestamp() function in the third SELECT. That's what you could do, too, apart from all the other correct answers.