c:/>set NLS_LANG=AMERICAN_AMERICA.US7ASCII
c:/>sqlplus eygle/eygle
SQL*Plus: Release 9.2.0.4.0 - Production on Tue Nov 4 01:19:57 2003
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production
SQL> insert into test values('测试');
1 row created.
SQL> select name,dump(name) from test;
NAME DUMP(NAME)
--------------------------------------------------
2bJT Typ=1 Len=4: 50,98,74,84
这时候我们发现，查询出来的是混乱的字符，我们把这些字符转换为2进制就是
110010   1100010   1001010   1010100
补全8位就是       00110010  01100010  01001010  01010100
我们把首位换成1   10110010  11100010  11001010  11010100
我们来看正确的存储:c:/>set nls_lang=AMERICAN_AMERICA.ZHS16GBK

c:/>sqlplus eygle/eygle

SQL*Plus: Release 9.2.0.4.0 - Production on Tue Nov 4 01:40:18 2003

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production

SQL> insert into test values('测试');

1 row created.

SQL> col dump(name) for a30
SQL> select name,dump(name) from test;

NAME DUMP(NAME)
---------- ------------------------------
测试 Typ=1 Len=4: 178,226,202,212

1 row selected.

我们把这个结果转换为2进制表示          10110010  11100010  11001010  11010100

这个结果正是我们前面乱码首位补全1后的结果。

这个测试说明在US7ASCII转换中文的时候除去了首位的 1,这样就丢失了元数据，导致乱码出现，NLS_LANG的转换作用由此可加一斑！

c:/>set nls_lang=AMERICAN_AMERICA.US7ASCII
c:/>sqlplus eygle/eygle
SQL*Plus: Release 9.2.0.4.0 - Production on Tue Nov 4 01:02:04 2003
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production
SQL> insert into test values('测试');
1 row created.
SQL> commit;
Commit complete.
SQL> select * from test;
NAME
----------
测试
1 row selected.
SQL> col dump(name) for a30
SQL> select name,dump(name) from test;
NAME       DUMP(NAME)
---------- ------------------------------
测试       Typ=1 Len=4: 178,226,202,212
1 row selected.
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               US7ASCII
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              9.2.0.4.0
20 rows selected.
SQL>