OSDBA and OSOPER
Two special operating system groups control database administrator connections
when using operating system authentication. These groups are generically referred to
as OSDBA and OSOPER. The groups are created and assigned specific names as part
of the database installation process. The specific names vary depending upon your
operating system and are listed in the following table:

The default names assumed by the Oracle Universal Installer can be overridden. How
you create the OSDBA and OSOPER groups is operating system specific.
Membership in the OSDBA or OSOPER group affects your connection to the database
in the following ways:
■ If you are a member of the OSDBA group and you specify AS SYSDBA when you
connect to the database, then you connect to the database with the SYSDBA system
privilege.
■ If you are a member of the OSOPER group and you specify AS SYSOPER when
you connect to the database, then you connect to the database with the SYSOPER
system privilege.
■ If you are not a member of either of these operating system groups and you
attempt to connect as SYSDBA or SYSOPER, the CONNECT command fails.

使用操作系统认证
1. 如果属于OSDBA , 则可使用AS SYSDBA连接
2. 如果属于OSOPER , 则可使用AS OSOPER连接
3. 如果不在这两个组中 , 却使用sysdba或sysoper连接的话 , connect命令失败