Oracle 12c中文亂碼，修改字符集的方法

在windows 7 64位上安裝Oracle 12c沒有設定字符集，采用的是操作系統默認字符集：WE8MSWIN1252，將字符集修改為：ZHS16GBK。由於過程不可逆，首先需要備份數據庫。

1.數據庫全備

2.查詢當前字符集

PARAMETER                                                    VALUE
------------------------------------------------------------ ------------------------------------------------------------
NLS_CHARACTERSET                                             WE8MSWIN1252

SQL>

3.關閉數據庫

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

4.啟動數據庫到mount狀態

SQL> startup mount
ORACLE instance started.

Total System Global Area 4982833152 bytes
Fixed Size                  2934600 bytes
Variable Size            2734688440 bytes
Database Buffers         2231369728 bytes
Redo Buffers               13840384 bytes
Database mounted.

5.限制session

SQL> alter system enable restricted session;

System altered.

6.查詢相關參數並修改，防止有任務自動啟動執行

SQL> show parameter job_queue_processes;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
job_queue_processes                       integer     1000

SQL> show parameter aq_tm_processes;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                            integer     1

SQL>  alter system set job_queue_processes=0;

System altered.

SQL> ALTER SYSTEM SET AQ_TM_PROCESSES=0;

System altered.

7.打開數據庫

SQL> alter database open  ;

Database altered.

8.修改字符集

SQL> alter database character set AL32UTF8;
alter database character set AL32UTF8
*
ERROR at line 1:
ORA-12712: new character set must be a superset of old character set

出現錯誤提示，新字符集必須是老字符集的超集，也就原來字符集是新字符集的子集，可以再Oracle官方文檔上查詢字符集包含關系。下面使用Oracle內部命令internal_use，跳過超集檢查，生產環境不建議使用此方法。

SQL> alter database character set internal_use AL32UTF8;

Database altered.

9.查詢當前字符集

SQL> select * from nls_database_parameters where parameter='NLS_CHARACTERSET';

PARAMETER                                                    VALUE
------------------------------------------------------------ ------------------------------------------------------------
NLS_CHARACTERSET                                                      AL32UTF8

10.關閉數據庫

SQL> shutdown immediate

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

11.啟動數據庫到mount狀態

SQL> startup mount
ORACLE instance started.

Total System Global Area 4982833152 bytes
Fixed Size                  2934600 bytes
Variable Size            2734688440 bytes
Database Buffers         2231369728 bytes
Redo Buffers               13840384 bytes
Database mounted.

12.將相關參數改回原來值

SQL>  alter system set job_queue_processes=1000;

System altered.

SQL> ALTER SYSTEM SET AQ_TM_PROCESSES=1;

System altered.

13.打開數據庫

SQL> alter database open  ;

Database altered.

原文地址：

Oracle 12c中文亂碼，修改字符集的方法