sys是Oracle數據庫中權限最高的帳號，具有create database的權限，而system沒有這個權限，sys的角色是sysdba，system的角色是sysoper。

其余就是他們兩個用戶共有的權限了：

startup/shutdown/dba兩個用戶都是可以管理的。

平時用system來管理數據庫就可以了。這個用戶的權限對于普通的數據庫管理來說已經足夠權限了。

SYSDBA

Perform STARTUP and SHUTDOWN operations

ALTER DATABASE: open, mount, back up, or change character set

CREATE DATABASE

CREATE SPFILE

ARCHIVELOG and RECOVERY

Includes the RESTRICTED SESSION privilege

Effectively, this system privilege allows a user to connect as user SYS.

SYSOPER

Perform STARTUP and SHUTDOWN operations

CREATE SPFILE

ALTER DATABASE OPEN/MOUNT/BACKUP

ARCHIVELOG and RECOVERY

Includes the RESTRICTED SESSION privilege

This privilege allows a user to perform basic operational tasks, but without the ability to look at user data