导出数据库：oracle 9206
导出客户端：echo $NLS_LANG
AMERICAN
服务器字符集：
SQL> select * from nls_database_parameters
  2  /

PARAMETER                      VALUE
------------------------------ --------------------------------------------------------------------------------
NLS_NCHAR_CHARACTERSET         UTF8
NLS_LANGUAGE                   AMERICAN
NLS_TERRITORY                  AMERICA
NLS_CURRENCY                   $
NLS_ISO_CURRENCY               AMERICA
NLS_NUMERIC_CHARACTERS         .,
NLS_CHARACTERSET               ZHS16CGB231280
NLS_CALENDAR                   GREGORIAN
NLS_DATE_FORMAT                DD-MON-RR
NLS_DATE_LANGUAGE              AMERICAN
NLS_SORT                       BINARY
NLS_TIME_FORMAT                HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT           DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT             HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT        DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY              $
NLS_COMP                       BINARY
NLS_LENGTH_SEMANTICS           BYTE
NLS_NCHAR_CONV_EXCP            FALSE
NLS_RDBMS_VERSION              9.2.0.6.0

导入数据库：
版本：ORACLE8174
客户端字符集：
[oracle@devp208 admin]$ echo $NLS_LANG
american_america.zhs16cgb231280
服务器字符集：
SQL> select * from nls_database_parameters
  2  /

PARAMETER                      VALUE
------------------------------ --------------------------------------------------------------------------------
NLS_LANGUAGE                   AMERICAN
NLS_TERRITORY                  AMERICA
NLS_CURRENCY                   $
NLS_ISO_CURRENCY               AMERICA
NLS_NUMERIC_CHARACTERS         .,
NLS_CHARACTERSET               ZHS16CGB231280
NLS_CALENDAR                   GREGORIAN
NLS_DATE_FORMAT                DD-MON-RR
NLS_DATE_LANGUAGE              AMERICAN
NLS_SORT                       BINARY
NLS_TIME_FORMAT                HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT           DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT             HH.MI.SSXFF AM TZH:TZM
NLS_TIMESTAMP_TZ_FORMAT        DD-MON-RR HH.MI.SSXFF AM TZH:TZM
NLS_DUAL_CURRENCY              $
NLS_COMP                       BINARY
NLS_NCHAR_CHARACTERSET         US7ASCII
NLS_RDBMS_VERSION              8.1.7.4.0

18 rows selected

开始我的做法：
1 在9I数据库的本地导出
导出前
export NLS_LANG=american_america.zhs16cgb231280
2 FTP到8I的服务器上
3 在8I的服务器上导入
$ imp filepub/Filedown001 file=client_file.dmp full=y ignore=y

Import: Release 8.1.7.4.0 - Production on Tue Dec 13 13:52:35 2005

(c) Copyright 2000 Oracle Corporation.  All rights reserved.


Connected to: Oracle8i Enterprise Edition Release 8.1.7.4.0 - Production
With the Partitioning option
JServer Release 8.1.7.4.0 - Production

IMP-00010: not a valid export file, header failed verification
IMP-00000: Import terminated unsuccessfully
[oracle@devp208 ~]$

后来意识到是数据库的版本不一致
做法如下：
在8I的服务器上导出：
[oracle@devp208 admin]$ exp filepub/Filedown001@download76 tables=(client_file) file=client_file.dmp

Export: Release 8.1.7.4.0 - Production on Tue Dec 13 14:09:17 2005

(c) Copyright 2000 Oracle Corporation.  All rights reserved.


Connected to: Oracle9i Enterprise Edition Release 9.2.0.6.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.6.0 - Production
Export done in ZHS16CGB231280 character set and UTF8 NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                    CLIENT_FILE          6 rows exported
Export terminated successfully without warnings.

同样在8I的服务器上导入：
[oracle@devp208 admin]$ imp filepub/Filedown001 file=client_file.dmp full=y ignore=y

Import: Release 8.1.7.4.0 - Production on Tue Dec 13 14:12:20 2005

(c) Copyright 2000 Oracle Corporation.  All rights reserved.


Connected to: Oracle8i Enterprise Edition Release 8.1.7.4.0 - Production
With the Partitioning option
JServer Release 8.1.7.4.0 - Production

Export file created by EXPORT:V08.01.07 via conventional path
import done in ZHS16CGB231280 character set and US7ASCII NCHAR character set
export server uses UTF8 NCHAR character set (possible ncharset conversion)
. importing FILEPUB's objects into FILEPUB
. . importing table                  "CLIENT_FILE"          6 rows imported
About to enable constraints...
Import terminated successfully without warnings.
[oracle@devp208 admin]$

但警告说存在字符集转换，请问各位，如何避免字符集转换？