Getting ORA-01401for NVARCHAR2 greater than 1000 chars.

Question

I have a table with column PATTERN NVARCHAR2(1024). When I try to insert 1024 chars I get an error -
INSERT INTO test VALUES('AAA..1024times')
ERROR at line 1:
ORA-01401: inserted value too large for column
but
INSERT INTO test VALUES(N'AAA..1024times') works. I can insert a string upto 1000 chars without using N'' . I would like to know why this happens and when to use N'' and when not. Is it safe to use N'' even if column is varchar2 and not nvarchar2 ?
I have following database settings-
PARAMETER VALUE
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_NUMERIC_CHARACTERS .,
NLS_CHARACTERSET AL32UTF8
NLS_CALENDAR GREGORIAN
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE AMERICAN
NLS_SORT BINARY
NLS_TIME_FORMAT HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY $
NLS_COMP BINARY
NLS_LENGTH_SEMANTICS BYTE
NLS_NCHAR_CONV_EXCP FALSE
NLS_NCHAR_CHARACTERSET AL16UTF16
NLS_RDBMS_VERSION 10.1.0.2.0

Answer 1

Try this (not tested):
import oracle.sql.CharacterSet;
CharacterSet csDB=CharacterSet.make(CharacterSet.ZHS32GB18030);
int byteLenDB = csDB.convert("your string").length;
Note, ZHS32GB18030 is currently supported as the client character set only. You should better not define a database with this character set. (See: Database Globalization Support Guide, Table A-9). It looks like we have to clarify this, because DBCA lists ZHS32GB18030 and CREATE DATABASE accepts it.
The DB character set does not seem to be available through any public API (though it is retrieved and stored internally). You have to query the database.
-- Sergiusz