首先，确认字符集是否修改的不彻底。
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);
如果上面的查询的确显示有多个字符集的设定，则进行如下处理：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是没有写在文档中的参数，用以强制完成字符集一致化
ALTER DATABASE CHARACTER SET INTERNAL_USE &CHARSET;
ALTER DATABASE NATIONAL CHARACTER SET INTERNAL_USE &NCHARSET; //该语句执行时，有些版本汇报异常，可以忽略
SHUTDOWN IMMEDIATE;
STARTUP;
转载自http://hi.baidu.com/itfit/item/951e74fb897263773c198b0e?qq-pf-to=pcqq.c2c