Oracle Basic Learning 2--oracle login with three authentication mechanisms

first, there are three default users of Oracle installation complete

? Sys: The owner of the database object, the highest permissions, password at the time of installation (password management) can be changed

? System: Database administrator, password is manager

? Scott: A regular user with a password of Tiger

see three different authentication mechanisms for connecting to Oracle

? Operating system verification (see below)

? Password file validation

? Database validation

Note: The first two apply to the system users, such as:Sys,system , etc.; the last one is for ordinary users, such asScott.

look at the startup process of Oracle

? Start "Listen" first

? The system user is then connected to the database without logging in (nolog)

? The database instance is then started (by the system user)

The conversion to command is as follows:

? lsnrctlStart (Start monitoring)

? sqlplus/nolog(no login)

Conn Sys/oracle as SYSDBA(System user connected to database)

? Starup(Start db instance)

Note: conn sys/oracle as Sysdba "/ "sys is the user name," / "oracel is a password. sysdba means "system database Administrator", with this identity, in fact, do not need a user name password to connect to oracle because this identity is connected using the "Operating system Authentication" method above, and the user name and password are not validated at all. So we can not write user name password: conn/as sysdba ("/ "Cannot omit , or can be written casually: conn KB/LBG as SYSDBA is no problem.

This explains "operating system validation", which is the equivalent of Windows authentication when we connect to SQL Server , because the Windows system administrator defaults to Oracle, The super Administrator of SQL Server is verified as follows:

Turn on Computer Management- -> Local Users and Groups- -> groups- ->ORA_DBA to see if a group member contains the currently logged-on Windows system administrator, for example ; (My current logon object is v-wangzhip)

　　

If present, it represents the Windows system Administrator, which is the DBA(database administrator) of Oracle . So do not write user name, password can be connected to Oracle by default, if you remove this administrator from ora_dba , then conn/as sysdba connection will prompt "Insufficient permissions".