select * from nls_database_parameters;

NLS_LANGUAGE	AMERICAN
NLS_TERRITORY	AMERICA
NLS_CURRENCY	$
NLS_ISO_CURRENCY	AMERICA
NLS_NUMERIC_CHARACTERS	.,
NLS_CHARACTERSET	UTF8
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	10.2.0.4.0


select '안녕하세요', length('안녕하세요'), lengthb('안녕하세요') from dual;

'안녕하세요' LENGTH('안녕하세요')        LENGTHB('안녕하세요')       
------- ---------------------- ---------------------- 
안녕하세요 5                      15 



create table test
( name1 varchar2(15)
, name2 varchar2(15 byte)
, name3 varchar2(15 char)
, name4 nvarchar2(10)
);


insert into test values('안녕하세요', '안녕하세요', '안녕하세요안녕하세요안녕하세요', '안녕하세요안녕하세요');
insert into test values('abcdefghijklmno', '123456789012345', 'abcdefghijklmno', 'abcdefghij');


select  name1, length(name1), lengthb(name1) 
,       name2, length(name2), lengthb(name2)
,       name3, length(name3), lengthb(name3)
,       name4, length(name4), lengthb(name4)
from test;


NAME1                           LENGTH(NAME1)          LENGTHB(NAME1)         
---------------                 ---------------------- ---------------------- 
안녕하세요                      5                      15                     
abcdefghijklmno                 15                     15                     



NAME2                           LENGTH(NAME2)          LENGTHB(NAME2)         
---------------                 ---------------------- ---------------------- 
안녕하세요                      5                      15                     
123456789012345                 15                     15                     



NAME3                           LENGTH(NAME3)          LENGTHB(NAME3)         
---------------                 ---------------------- ---------------------- 
안녕하세요안녕하세요안녕하세요  15                     45                     
abcdefghijklmno                 15                     15                     



NAME4                           LENGTH(NAME4)          LENGTHB(NAME4)         
----------                      ---------------------- ---------------------- 
안녕하세요안녕하세요            10                     20                     
abcdefghij                      10                     20                     








UTF8                Max Btye    영문                        한글
------------------------------------------------------------------------------------------------------------
varchar2(15)        15 Byte     15 Byte = 15 * 1 Byte       15 Byte = 5 * 3 Byte
varchar2(15 byte)   15 Byte     15 Byte = 15 * 1 Byte       15 Byte = 5 * 3 Byte
varchar2(15 char)   45 Byte     15 Byte = 15 * 1 Byte       45 Byte = 15 * 3 Byte
nvarchar2(10)       20 Byte     20 Byte = 10 * 2 Byte       20 Byte = 10 * 2 Byte