在Oracle的11g之前的版本中密码是不区分大小写的（使用双引号强制除外）。
在Oracle的11g以及以后的版本中对此有所增强。从此密码有了大小写的区分。
这个大小写敏感特性是通过SEC_CASE_SENSITIVE_LOGON参数来控制的。
1.Oracle 11gR2官方文档解释:
http://download.oracle.com/docs/cd/E11882_01/server.112/e10820/initparams218.htm#REFRN10299
SEC_CASE_SENSITIVE_LOGON
Property Description
Parameter type Boolean
Default value true
Modifiable ALTER SYSTEM
Range of values true | false
Basic No
SEC_CASE_SENSITIVE_LOGON enables or disables password case sensitivity in the database.
Values:
true
Database logon passwords are case sensitive.
false
Database logon passwords are not case sensitive.
2.测试一下
[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Mon Feb 12 16:14:53 2018
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
#创建用n1 密码 ni
SQL> create use n1 identified by n1;
SQL> grant connect,resource to n1;
#查看sec_case_sensitive_logon 参数设置 默认是 TRUE 即开启登陆大小写敏感！
SQL> show parameter sec
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_securefile string PERMITTED
optimizer_secure_view_merging boolean TRUE
sec_case_sensitive_logon boolean TRUE
sec_max_failed_login_attempts integer 10
sec_protocol_error_further_action string CONTINUE
sec_protocol_error_trace_action string TRACE
sec_return_server_release_banner boolean FALSE
sql92_security boolean FALSE
#使用大写的密码登陆 登陆失败
SQL> conn n1/N1
ERROR:
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
SQL> conn / as sysdba
Connected.
#动态修改系统参数 为 false 不验证大小写
SQL> alter system set sec_case_sensitive_logon = false;
System altered.
#再次使用大写密码登陆 成功
SQL> conn n1/N1
Connected.
3.延伸测试(sec_case_sensitive_logon 参数只是控制登陆时是否校验大小写,密码还是会进按照世纪的大小写进行存储的！)
SQL> show parameter sec_case_sensitive_logon
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
sec_case_sensitive_logon boolean FALSE
#创建用户 密码包含大小写
SQL> create user test11 identified by testAbcD ;
User created.
SQL> grant connect to test11;
Grant succeeded.
#测试链接 大小写不敏感
SQL> conn test11/testabcd
Connected.
SQL> conn / as sysdba
Connected.
#修改为大小写敏感
SQL> alter system set sec_case_sensitive_logon = true;
System altered.
#用错误的密码无法登陆
SQL> conn test11/testabcd
ERROR:
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
#包含大小写的密码,登陆成功！
SQL> conn test11/testAbcD
Connected.
SQL>