较好的实践是，oracle的密码操作通过profile来实现，而资源则是通过资源消费组来控制，profile其实是种限制。
通过profile来控制密码的使用，大抵有四：
1） 密码的历史
    在这里，有两个参数：password_reuse_time和password_reuse_max，比较好的实践是，这两个参数当关联起来使用。 如：password_reuse_time=30，password_reuse_max=10，
    用户可以在30天以后重用该密码，要求密码必须被改变超过10次。
    实验：
    会话1：sys
    sys@ORCL> create profile p1 limit password_reuse_time 1/1440 password_reuse_max 1;

    Profile created.
   
    sys@ORCL> alter user scott profile p1;
   
    User altered.
   
    sys@ORCL> alter user scott password expire;
   
    User altered.
   
    sys@ORCL> alter profile p1 limit password_reuse_time 5/1440 password_reuse_max 1;--5分钟后可重用该密码，但这期间必须要被改成其他密码一次
   
    Profile altered.
   
    sys@ORCL> alter user scott password expire;
   
    User altered.
    会话2：scott
    scott@ORCL> exit;
    Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
    With the Partitioning, OLAP and Data Mining options
    [oracle@localhost ~]$ sqlplus /nolog
   
    SQL*Plus: Release 10.2.0.1.0 - Production on Mon Sep 3 01:11:09 2012
   
    Copyright (c) 1982, 2005, Oracle.  All rights reserved.
   
    idle> conn scott/oracle
    ERROR:
    ORA-28001: the password has expired
   
   
    Changing password for scott
    New password:                --使用原密码，即oracle
    Retype new password:
    ERROR:
    ORA-28007: the password cannot be reused
   
   
    Password unchanged
    idle> conn scott/oracle
    ERROR:
    ORA-28001: the password has expired
   
   
    Changing password for scott
    New password:               --使用新密码，改成think
    Retype new password:
    Password changed
    Connected.
    会话1：sys
    sys@ORCL> alter user scott password expire;

    User altered.
    会话2：scott
    scott@ORCL> exit;
    Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
    With the Partitioning, OLAP and Data Mining options
    [oracle@localhost ~]$ sqlplus /nolog
   
    SQL*Plus: Release 10.2.0.1.0 - Production on Mon Sep 3 01:19:04 2012
   
    Copyright (c) 1982, 2005, Oracle.  All rights reserved.
   
    idle> conn scott/think
    ERROR:
    ORA-28001: the password has expired
   
   
    Changing password for scott
    New password:    &