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HomeDatabaseMysql TutorialOracle中存取控制介绍

用户环境文件是指定资源限制的命名集,可赋给ORACLE数据库的有效的用户。利用用户环境文件可容易地管理资源限制。要使用用户

  Oracle使用多种不同的机制管理数据库安全性,其中有两种机制:模式和用户。模式为模式对象的集合,模式对象如表、视图、过程和包等。第一数据库有一组模式。

  每一Oracle数据库有一组合法的用户,可存取一数据库,可运行一数据库应用和使用该用户各连接到定义该用户的数据库。当建立一数据库用户时,对该用户建立一个相应的模式,模式名与用户名相同。一旦用户连接一数据库,该用户就可存取相应模式中的全部对象,一个用户仅与同名的模式相联系,所以用户和模式是类似的。

  用户的存取权利受用户安全域的设置所控制,在建立一个数据库的新用户或更改一已有用户时,安全管理员对用户安全域有下列决策:

  是由数据库系统还是由操作系统维护用户授权信息。

  设置用户的缺省表空间和临时表空间。

  列出用户可存的表空间和在表空间中可使用空间份额。

  设置用户资源限制的环境文件,该限制规定了用户可用的系统资源的总量。

  规定用户具有的特权和角色,可存取相应的对象。

  每一个用户有一个安全域,它是一组特性,可决定下列内容:

  用户可用的特权和角色;

  用户可用的表空间的份额;

  用户的系统资源限制。

  (1)用户鉴别:

  为了防止非授权的数据库用户的使用,ORACLE提供二种确认方法

  操作系统确认和相应的ORACLE数据库确认。

  如果操作系统允许,ORACLE可使用操作系统所维护的信息来鉴定用户。由操作系统鉴定用户的优点是:

  用户可更方便地连接到ORACLE,,不需要指定用户名和口令。

  对用户授权的控制集中在操作系统,ORACLE不需要存储和管理用户口令。然而用户名在数据库中仍然要维护。

  在数据库中的用户名项和操作系统

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