Sys--system-sysdba-sysoper User Differences

When the Oracle database is installed, both the SYS and system accounts are created automatically.
1.
SYS: The default password is Change_on_install and is granted to the DBA role
System: Default password is manager, and DBA role is granted
2.
SYS: This account is equivalent to the SA account in SQL Server, or the administrator in the XP system, or the root account on the Linux system, is a super account, has the most permissions and can complete all the management tasks of the database. All of the base tables, views, and so on in Oracle are stored in the data dictionary in the SYS schema, similar to the master database in SQL Server, which stores all the most primitive, basic, and critical system structures, data, and so on. Therefore, all the objects in the SYS schema are not allowed to be modified by the user or database administrator and are not recommended for creating the SYS schema object.
System: This account, in addition to the inability to complete backup recovery and all administrative tasks for databases other than upgrades, is typically used to create tables or views that are used to view management information, as well as internal tables or internal views that are used by different Oracle database options and tools. It is also not recommended to use the system schema to create some tables or views that are not related to management.
3.
SYSDBA has the highest system privileges, and after logging in, use Show user to view the SYS
SYSDBA is a management Oracle instance, its existence does not depend on the entire database starts completely, as long as the instance launches, it already exists, is logged in as SYSDBA identity (is a login authentication identity), mount the database, open the database. Only if the database is open, or when the entire database is fully booted, the DBA role (which corresponds to the set of operational permissions for the Oracle instance object) has the basis for existence! Sysoper and SYSDBA are not roles, and the DBA role does not contain these two kinds of permissions.
Sysoper is mainly used to start, close the database, Sysoper log on after the use of command Show user to view the public.
4, the choice of the role when landing is normal, this is for all ordinary users, after landing its schema is itself.
5.
Sysoper permissions to perform the following actions
startup, shutdown
Create SPFile
ALTER DATABASE [Mount | open | close | dismount]
alter [Database | tablespace] [begin | end] Backup
ALTER DATABASE recover
Restricted session
SYSDBA Permissions
In addition to executing all of the above commands, you can create databases, delete databases, archive database logs, perform incomplete restores, and create other Sysoper and SYSDBA users