select * from v$nls_parameters  where parameter='NLS_CHARACTERSET'
select * from  nls_database_parameters where parameter='NLS_CHARACTERSET'
select * from props$ where name='NLS_CHARACTERSET'

select * from  nls_database_parameters where parameter='NLS_NCHAR_CHARACTERSET'
select * from  nls_database_parameters where parameter='NLS_NCHAR_CHARACTERSET'
select * from props$ where name='NLS_NCHAR_CHARACTERSET'

select userenv('language') from dual

 --DataFile联机
ALTER TABLESPACE BSS11 ONLINE
ALTER DATABASE 'BSS_03.dbf' ONLINE

--DataFile脱机
ALTER TABLESPACE BSS11 OFFLINE      --作用对象：表空间BSS11的所有datafile
ALTER DATABASE 'BSS_03.dbf' OFFLINE  ---作用对象：BSS_03.dbf，就一个datafile

--resize datafile
ALTER DATABASE DATAFILE 'BSS_03.dbf' RESIZE 500M;