Oracle字符集详解：图表解析与中文乱码解决方案

经常碰到SQLPLUS展现乱码的问题，字符集和相关的定义都有说明但是很少有能把这些关系说的很简单易懂的。

在此之前我们需要搞清楚三个概念，操作系统字符集，客户端字符集，Oracle字符集：

操作系统字符集：对应的参数是LANG，这个参数应该是Oracle数据库的超集，如果操作系统不支持，那么我们的数据就会乱码。这里的操作系统指的是客户端的操作系统。服务器端的操作系统不会影响数据的存取。

数据库字符集：NLS_CHARACTERSET，可以在nls_database_parameters中查看当前数据库的字符集，安装数据库的时候选择，一般不修改，不过在新的字符集是现有字符集的严格超集的情况下可以改，其他情况下修改可能导致数据库异常。例如将UTF8字符集修改为AL32UTF8

关于子集超集的映射关系，见如下Oracle官网的文档的Binary Subset-Superset Pairs。

http://docs.oracle.com/database/121/NLSPG/applocaledata.htm#NLSPG591 

客户端字符集：对应的参数是NLS_LANG，如果客户端未设置，此时则取的是安装时数据库的默认参数

为了帮助理解，我画了一张图如下，图中标红部分如果一致表示数据的存储方式一致，即如果LANG、NLS_LANG、NLS_CHARACTERSET的编码是一致的如UTF8，那么数据的传输过程中不会异常，字符乱码只是显示问题。

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1、操作系统字符集

Linux下首先locale 查看字符集

[oracle@oddpc ~]$ locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MOnETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHOnE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=
[oracle@oddpc ~]$ echo $LANG
en_US.UTF-8

2、该主机并未安装中文支持包，设置LANG后可以效果如下，显然无路如何调整NLS_LANG在这台机器上都无法展现中文

[oracle@evenpc ~]$ export LANG=zh_CN.utf8
[oracle@evenpc ~]$ date
2016? 10? 13? ??? 15:17:01 CST

3、安装中文支持包，使用yum -y groupinstall chinese-support 可以安装中文支持包，安装过程略过，安装完毕后可以正常显示中文

[oracle@oddpc ~]$ export LANG=zh_CN.utf8
[oracle@oddpc ~]$ date
2016年 10月 13日 星期四 15:14:19 CST

4、接下来就是展现测试，我安装了两个数据库实例PROD1和PROD5，PROD1 的字符集是WE8MSWIN1252，PROD5的字符集是AL32UTF8

默认情况下NLS_LANG是空的，此时NLS_LANG取默认安装时的值，PROD1是AMRICAN,PROD5是SIMPLIFIED CHINESE

[oracle@oddpc ~]$ echo $NLS_LANG
[oracle@oddpc ~]$ 

SQL> show parameter lang        

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
nls_date_language                    string
nls_language                         string      AMERICAN

SQL> select sysdate from dual;

SYSDATE
---------
13-OCT-16

PROD5

SQL> show parameter lang  

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
nls_date_language                    string
nls_language                         string      SIMPLIFIED CHINESE

SQL> select sysdate from dual;

SYSDATE
----------
13-10?-16

5、PROD5 发生乱码，PROD1英文正常,设置下NLS_LANG参数

PROD1 的结果如下，可以看到提示信息已经变成中文，但是由于字符集非UTF8中文字符存入后将乱码

[oracle@oddpc ~]$ export NLS_LANG="SIMPLIFIED CHINESE_CHINA.UTF8"
[oracle@oddpc ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on 星期四 10月 13 15:42:46 2016

Copyright (c) 1982, 2011, Oracle.  All rights reserved.


连接到: 
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> show parameter lang

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
nls_date_language                    string                            SIMPLIFIED CHINESE
nls_language                         string                            SIMPLIFIED CHINESE
SQL> show parameter db_name

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
db_name                              string                            PROD1
SQL> show parameter lang

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
nls_date_language                    string                            SIMPLIFIED CHINESE
nls_language                         string                            SIMPLIFIED CHINESE
SQL> select sysdate from dual;

SYSDATE
------------
13-10? -16
SQL> select * from nls_database_parameters;

PARAMETER                                VALUE
---------------------------------------- ----------------------------------------
NLS_LANGUAGE                             AMERICAN
NLS_TERRITORY                            AMERICA
NLS_CURRENCY                             $
NLS_ISO_CURRENCY                         AMERICA
NLS_NUMERIC_CHARACTERS                   .,
NLS_CHARACTERSET                         WE8MSWIN1252
NLS_CALENDAR                             GREGORIAN
NLS_DATE_FORMAT                          DD-MON-RR
NLS_DATE_LANGUAGE                        AMERICAN
NLS_SORT                                 BINARY
NLS_TIME_FORMAT                          HH.MI.SSXFF AM

PARAMETER                                VALUE
---------------------------------------- ----------------------------------------
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_NCHAR_CHARACTERSET                   AL16UTF16
NLS_RDBMS_VERSION                        11.2.0.3.0

已选择20行。
 
 
PROD5的结果如下，此时PROD5显示正常
[oracle@oddpc ~]$ export NLS_LANG="SIMPLIFIED CHINESE_CHINA.UTF8"
[oracle@oddpc ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.3.0 Production on 星期四 10月 13 15:46:36 2016

Copyright (c) 1982, 2011, Oracle.  All rights reserved.


连接到: 
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> show parameter db_name

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
db_name                              string                            PROD5
SQL> select sysdate from dual;

SYSDATE
------------
13-10月-16

SQL> show parameter lang

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
nls_date_language                    string                            SIMPLIFIED CHINESE
nls_language                         string                            SIMPLIFIED CHINESE
SQL> select * from nls_database_parameters;

PARAMETER                                VALUE
---------------------------------------- ----------------------------------------
NLS_LANGUAGE                             AMERICAN
NLS_TERRITORY                            AMERICA
NLS_CURRENCY                             $
NLS_ISO_CURRENCY                         AMERICA
NLS_NUMERIC_CHARACTERS                   .,
NLS_CHARACTERSET                         AL32UTF8
NLS_CALENDAR                             GREGORIAN
NLS_DATE_FORMAT                          DD-MON-RR
NLS_DATE_LANGUAGE                        AMERICAN
NLS_SORT                                 BINARY
NLS_TIME_FORMAT                          HH.MI.SSXFF AM

PARAMETER                                VALUE
---------------------------------------- ----------------------------------------
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_NCHAR_CHARACTERSET                   AL16UTF16
NLS_RDBMS_VERSION                        11.2.0.3.0

已选择20行。
 

总结：通过以上的实验可以看出，客户端展现是否乱码是由NLS_LANG决定，发生中文乱码的情况下，首先查看数据库的NLS_CHARACTERSET是否支持中文存储，如果不支持，无论如何设置均无法正常显示中文。Oracle官方文档上给出了各种语言的编码支持如下。



http://docs.oracle.com/database/121/NLSPG/applocaledata.htm#NLSPG593
Table A-13 Languages and Character Sets Supported by LCSSCAN and GDK


Language
Character Sets




Arabic


AL16UTF16, AL32UTF8, AR8ISO8859P6, AR8MSWIN1256, UTF8




Bulgarian


AL16UTF16, AL32UTF8, CL8ISO8859P5, CL8MSWIN1251, UTF8




Catalan


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Croatian


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Czech


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Danish


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Dutch


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




English


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Estonian


AL16UTF16, AL32UTF8, NEE8IOS8859P4, UTF8




Finnish


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




French


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




German


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Greek


AL16UTF16, AL32UTF8, EL8ISO8859P7, EL8MSWIN1253, UTF8




Hebrew


AL16UTF16, AL32UTF8, IW8ISO8859P8, IW8MSWIN1255, UTF8




Hindi


AL16UTF16, AL32UTF8, IN8ISCII, UTF8




Hungarian


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Indonesian


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Italian


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Japanese


AL16UTF16, AL32UTF8, ISO2022-JP, JA16EUC, JA16SJIS, UTF8




Korean


AL16UTF16, AL32UTF8, ISO2022-KR, KO16KSC5601, KO16MSWIN949, UTF8




Latvian


AL16UTF16, AL32UTF8, NEE8ISO8859P4, UTF8




Lithuanian


AL16UTF16, AL32UTF8, NEE8ISO8859P4, UTF8




Malay


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Norwegian


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Persian


AL16UTF16, AL32UTF8, AR8MSWIN1256, UTF8




Polish


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Portuguese


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Romanian


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Russian


AL16UTF16, AL32UTF8, CL8ISO8859P5, CL8KOI8R, CL8MSWIN1251, RU8PC866, UTF8




Serbian


AL16UTF16, AL32UTF8, CL8ISO8859P5, CL8MSWIN1251, UTF8




Simplified Chinese


AL16UTF16, AL32UTF8, HZ-GB-2312, UTF8, ZHS16GBK, ZHS16CGB231280




Slovak


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Slovenian


AL16UTF16, AL32UTF8, EE8ISO8859P2, EE8MSWIN1250, UTF8




Spanish


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Swedish


AL16UTF16, AL32UTF8, US7ASCII, UTF8, WE8ISO8859P1, WE8ISO8859P15, WE8MSWIN1252




Thai


AL16UTF16, AL32UTF8, TH8TISASCII, UTF8




Traditional Chinese


AL16UTF16, AL32UTF8, UTF8, ZHT16MSWIN950




Turkish


AL16UTF16, AL32UTF8, TR8MSWIN1254, UTF8, WE8ISO8859P9




Ukranian


AL16UTF16, AL32UTF8, CL8ISO8859P5, CL8MSWIN1251, UTF8




Vietnamese


AL16UTF16, AL32UTF8, VN8VN3, UTF8