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書名： Oracle Database 12c Security Cookbook
作者名： Zoran Pavlovi? Maja Veselica
本章字數： 471字
更新時間： 2021-07-02 16:43:15

Creating a common user

A common user is a user created in the root container, which has the same identity across all containers. The main purpose of a common user is to perform "infrastructure" administrative tasks, such as starting up a CDB, plugging and unplugging PDBs, and opening PDBs. There are two types of common users: Oracle-supplied (for example, SYS and SYSTEM) and user-created common users.

Getting ready

To complete this recipe, you'll need an existing common user who has create user privilege granted commonly.

How to do it...

Connect to the root container as a common user who has create user privilege granted commonly (for example, c##zoran or system user):
```
       SQL> connect c##zoran@cdb1 
```

Create a common user (for example, c##maja):

       c##zoran@CDB1> create user c##maja identified by oracle1 container=all;

How it works...

c##maja is actually not a single user, but each container has a user named c##maja and the passwords must be the same.

Figure 4

Rules/guidelines for creating and managing common users

There are a few rules you should be aware of:

The name of a common user must be unique across all containers. In version 12.1.0.1, it must begin with c## or C## unless you change the internal parameter common_user_prefix (which you shouldn't do on a production system without approval from Oracle Support) and, in version 12.1.0.2, it is best practice to use a prefix (default value c## or C##). However, you can choose it by changing the value of the common_user_prefix parameter (this naming convention doesn't apply to Oracle-supplied users in either version).
A common user can have different privileges in different containers.
The schemas for a common user may contain different objects in different containers.

The column oracle_maintained (in DBA_USERS) provides information as to whether a user is created and maintained by Oracle-supplied scripts:

c##zoran@CDB1> select username, oracle_maintained from dba_users where username='SYSTEM' or username='C##ZORAN';

USERNAME O 
--------------- - 
SYSTEM Y 
C##ZORAN N

There's more...

You can also create common users by using Oracle Enterprise Manager Cloud Control (OEM) 12c.

How to create a common user using OEM 12c

Start OEM 12c and log in using user SYSMAN or SYSTEM.
From the Databases page, select the root database in which you want to create a common user. The database home page appears.
From the Administration menu, select Security (a drop-down menu) and then Users (see Figure 5):

Figure 5
If prompted, log in to the root as a common user who has a create user privilege (for example, c##zoran; see Figure 6):

Figure 6
Click on the Create button (see Figure 7):

Figure 7
To create a common user, it is enough to fill out the following fields on the General tab: Name (for example, c##john), Enter Password, and Confirm Password (see Figure 8) and then click on the OK button:

Figure 8

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Oracle Database 12c Security Cookbook