Why can Oracle users who do not have permissions log on with sysdba?

I created a user, createuserlisiidentifiedbylisi. When I log on with sqlplus: cmd-gt; sqlpluslisilisi cannot access

I created a user, create user lisi identified by lisi. When I log on with sqlplus: cmd-gt; sqlplus lisi/lisi cannot enter

I created a user, create user lisi identified by lisi. When I log on with sqlplus:

Cmd-> sqlplus lisi/lisi cannot go in-> then lisi as sysdba will go in, so I have doubts.

Then I went to the Administrator and deleted the lisi user.

Cmd-> sqlplus lisi/lisi cannot go in-> then lisi as sysdba will go in, and the question will go deeper.

Three answers:

Answer 1:

For windows operating systems, after the Oracle database is installed, a user group named ORA_DBA is automatically installed in the operating system.

SYSDBA is used to log on to the database without verifying the SYS password. You can also create a user group named ORA_SID_DBA (whose SID is the Instance name ).

Have the preceding privileges. This is why you are a system user when you can show,

Solution 2:

To put it simply, oracle should consider that you are sysdba with the following three conditions:

1. You have not set the password file for oracle (because oracle does not authenticate users logging on with sysdba by default)

2. you log on as an operating system administrator (no matter who logs on to your computer, as long as you log on as an administrator, oracle recognizes it as sysdba. You can try logging on to the operating system as a guest account, in this case, oracle won't recognize you as a DBA );

3. You Log On as sysdba (as long as you connect to the as sysdba, no matter which user name and password you added before, oracle considers you to log on as sysdba, and the user is sys)

When one of the preceding three conditions is not met, the user you log on to is not sys. If the user you log on to is not authorized as dba, then his permissions must be common permissions.

Solution 3:

The writing method is acceptable, but with the addition of as sysdba, you are logged on to sysdba, and it has nothing to do with the previous user. If you create a new user user1, for example, create user user1 identfied by 123, and then grant the login permission to him using the sys account, you can directly conn user1/123, so that the connection is user1, if you are conn user1/123 as sysdba, you are still connected to sysdba, and there is no relationship with the previous user1.

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