常见情形:从服务器备份Oracle数据库后再到本地机器上还原Oracle数据库的时候经常会碰见数据库字符编码不一致的情况，可以用以下命令来修改本地的Oracle数据库字符编码，然后顺利还原Oracle数据库到本地机器上
操作指令：
[oracle@gpdb ~]$ sqlplus /nolog
SQL> conn /as sysdba;
SQL>select userenv(‘language‘) from dual;
SQL>SHUTDOWN IMMEDIATE
SQL>STARTUP MOUNT
SQL>ALTER SYSTEM ENABLE RESTRICTED SESSION;
SQL>ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
SQL>ALTER SYSTEM SET AQ_TM_PROCESSES=0;
SQL>ALTER DATABASE OPEN;
SQL>ALTER DATABASE CHARACTER SET INTERNAL_USE US7ASCII;
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP;
SQL>select userenv(‘language‘) from dual;
常见的Oracle字符集有ZHS16GBK、AL32UTF8、US7ASCII等?