sys、system、sysdba和sysoper的区别

note:sys is role ,but sysdba and sysoper is privilege

sys
建库时自动创建，并被赋予DBA角色。所有的数据字典的基础表和视图均建立在该schema中。不应手工修改其中的内容或在该schema中建立对象。
system
建库时自动创建，并被赋予DBA角色。管理信息及数据库选项和工具使用的内部表和视图建立在该schema中。不应手工修改其中的内容或在该schema中建立对象。
DBA角色
建库时自动创建，包含大部分数据库权限，但不包括sysdba和sysoper权限。
sysdba
■ Perform. STARTUP and SHUTDOWN operations
■ ALTER DATABASE: open, mount, back up, or change character set
■ CREATE DATABASE
■ DROP DATABASE
■ CREATE SPFILE
■ ALTER DATABASE ARCHIVELOG
■ ALTER DATABASE RECOVER
■ Includes the RESTRICTED SESSION privilege
Effectively, this system privilege allows a user to connect as user SYS.
sysdba连接上来的schema是sys


sysoper
■ Perform. STARTUP and SHUTDOWN operations
■ CREATE SPFILE
■ ALTER DATABASE OPEN/MOUNT/BACKUP
■ ALTER DATABASE ARCHIVELOG
■ ALTER DATABASE RECOVER (Complete recovery only. Any form
of incomplete recovery, such as UNTIL
TIME|CHANGE|CANCEL|CONTROLFILE requires connecting as
SYSDBA.)
■ Includes the RESTRICTED SESSION privilege
This privilege allows a user to perform. basic operational tasks, but
without the ability to look at user data.
sysoper连接上来的shcema是public