1. SYS用戶具有DBA權限，并且擁有SYS模式，只能通過SYSDBA登陸數據庫。是Oracle數據庫中權限最高的帳號 SYSTEM具有DBA權限。但沒有SYSDBA權限。平常一般用該帳號管理數據庫就可以了。 2. （1）sys -- sysdba system --sysoper （2）startup/shutdown/dba管理兩個都能做
（3）sys擁有數據字典(dictionay),或者說dictionay屬于sys schema
（4）sysdba比sysoper多了一個create database的權限 3. 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
