oracle19c 修改字符集

环境：centos7.6

　　oracle 19c

修改过程：

shutdown immediate;
startup mount;
ALTER SYSTEM ENABLE RESTRICTED SESSION; 
ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
ALTER SYSTEM SET AQ_TM_PROCESSES=0;
alter database open; 
ALTER DATABASE character set INTERNAL_USE ZHS16GBK;