"Not a valid month" on an INSERT statement

Question

I have an sql statement:

Insert into MYSCHEMA.TABLE1 (ID,MY_DATE) values (167600,to_timestamp('15-APR-14 01.36.58.803000000 PM','DD-MON-RR HH.MI.SS.FF AM'));

As I read this format is correct (as described here) but oracle returns an error SQL Error: ORA-01843: not a valid month. Any idea how to solve this problem? I use Oracle Database 11b Express Edition.

Answer 1

Unless you have a trigger on the table that is setting a date or timestamp column, which would give some indication in the full error stack, it sounds like your NLS_DATE_LANGUAGE is not expecting an English-language month abbreviation.

What you have is valid in English:

alter session set nls_timestamp_format = 'RR/MM/DD HH24:MI:SSXFF';
alter session set nls_date_language ='ENGLISH';

select to_timestamp('15-APR-14 01.36.58.803000000 PM',
  'DD-MON-RR HH.MI.SS.FF AM') as my_date
from dual;

MY_DATE                   
---------------------------
14/04/15 13:36:58.803000000 

But if your session's default date language is Polish (guessing from your profile) it will give this error - with the error message still in English:

alter session set nls_date_language ='POLISH';

select to_timestamp('15-APR-14 01.36.58.803000000 PM',
  'DD-MON-RR HH.MI.SS.FF AM') as my_date
from dual;

SQL Error: ORA-01843: not a valid month
01843. 00000 -  "not a valid month"

If you don't want to set your session to English you can override that for a specific statement by giving the optional third parameter to to_timestamp():

alter session set nls_date_language ='POLISH';

select to_timestamp('15-APR-14 01.36.58.803000000 PM',
  'DD-MON-RR HH.MI.SS.FF AM',
  'NLS_DATE_LANGUAGE=ENGLISH') as my_date
from dual;

MY_DATE                   
---------------------------
14/04/15 13:36:58.803000000 

You can also avoid the issue entirely by using month numbers instead of month names, or using the ANSI timestamp literal syntax:

select timestamp '2014-04-15 13:36:58.803' from dual;

TIMESTAMP'2014-04-1513:36:58.803'
---------------------------------
14/04/15 13:36:58.803000000       

These methods also all work for date columns; the to_date() function is affected by NLS settings in the same way and has the same optional date language parameter.