A character set determines what languages can be represented in the database.
Oracle recommends Unicode AL32UTF8 as the database character set. Unicode is the universal character set that supports most of the currently spoken languages of the world.
select * from nls_database_parameters where parameter='NLS_CHARACTERSET'; PARAMETER VALUE --------------------- ------------ NLS_CHARACTERSET AL32UTF8
SQL> ; 1* SELECT * FROM NLS_DATABASE_PARAMETERS SQL> / PARAMETER VALUE ---------------------------------- ----------------------------- NLS_RDBMS_VERSION 12.1.0.2.0 NLS_NCHAR_CONV_EXCP FALSE NLS_LENGTH_SEMANTICS BYTE NLS_COMP BINARY NLS_DUAL_CURRENCY $ NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZR NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM NLS_TIME_FORMAT HH.MI.SSXFF AM NLS_SORT BINARY NLS_DATE_LANGUAGE AMERICAN NLS_DATE_FORMAT DD-MON-RR NLS_CALENDAR GREGORIAN NLS_NUMERIC_CHARACTERS ., NLS_NCHAR_CHARACTERSET AL16UTF16 NLS_CHARACTERSET AL32UTF8 NLS_ISO_CURRENCY AMERICA NLS_CURRENCY $ NLS_TERRITORY AMERICA NLS_LANGUAGE AMERICAN 20 rows selected.
SQL> show parameter nls NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ nls_calendar string nls_comp string BINARY nls_currency string nls_date_format string nls_date_language string nls_dual_currency string nls_iso_currency string nls_language string AMERICAN nls_length_semantics string BYTE nls_nchar_conv_excp string FALSE nls_numeric_characters string nls_sort string nls_territory string AMERICA nls_time_format string nls_time_tz_format string nls_timestamp_format string nls_timestamp_tz_format string
It is very difficult to change characterset after installation. Using above posted query it is easy to get characterset.