首先，確認字符集是否修改的不徹底。
SELECT DISTINCT (NLS_CHARSET_NAME(CHARSETID)) CHARACTERSET,
DECODE(TYPE#, 1,
DECODE(CHARSETFORM, 1, 'VARCHAR2', 2, 'NVARCHAR2', 'UNKOWN'),
9,
DECODE(CHARSETFORM, 1, 'VARCHAR', 2, 'NCHAR VARYING', 'UNKOWN'),
96,
DECODE(CHARSETFORM, 1, 'CHAR', 2, 'NCHAR', 'UNKOWN'),
112,
DECODE(CHARSETFORM, 1, 'CLOB', 2, 'NCLOB', 'UNKOWN')) TYPES_USED_IN
FROM SYS.COL$
WHERE CHARSETFORM IN (1, 2)
AND TYPE# IN (1, 9, 96, 112);
如果上面的查詢的確顯示有多個字符集的設定，則進行如下處理：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;
COL VALUE NEW_VALUE CHARSET
SELECT VALUE FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER='NLS_CHARACTERSET';
COL VALUE NEW_VALUE NCHARSET
SELECT VALUE FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER='NLS_NCHAR_CHARACTERSET';
--INTERNAL_USE是沒有寫在文檔中的參數，用以強制完成字符集一致化
ALTER DATABASE CHARACTER SET INTERNAL_USE &CHARSET;
ALTER DATABASE NATIONAL CHARACTER SET INTERNAL_USE &NCHARSET; //該語句執行時，有些版本匯報異常，可以忽略
SHUTDOWN IMMEDIATE;
STARTUP;
轉載自http://hi.baidu.com/itfit/item/951e74fb897263773c198b0e?qq-pf-to=pcqq.c2c