1.用户创建
1）全局用户
CBD$ROOT中创建用户默认container=all,且只能创建全局用户（必须以c##开头）,该全局用户在CDB$ROOT和所有PDBs中都会被创建，但PDBs中的该全局用户必须另外授权才能访问PDBs中的资源。
PDBs中默认且也只能创建本地用户（一定不能以c##开头）。
[oracle@rac19c1 ~]$ sqlplus / as sysdba
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL>
SQL> create user c##usr1 identified by usr1;
User created.
SQL> create user c##usr2 identified by usr2 container=all;
User created.
SQL> colu username for a30
SQL> select username,con_id,user_id from cdb_users where username like 'C##USR%';
USERNAME CON_ID USER_ID
------------------------------ ---------- ----------
C##USR1 1 106
C##USR2 1 107
C##USR1 3 107
C##USR2 3 109
2）本地用户
SQL> alter session set container=pdb1;
Session altered.
SQL> create user usr3 identified by usr3;
User created.
SQL> create user usr4 identified by usr4 container=current;
User created.
SQL> select username,con_id,user_id from cdb_users where username like 'USR%';
USERNAME CON_ID USER_ID
------------------------------ ---------- ----------
USR4 3 111
USR3 3 110
2.用户授权
默认情况下，只会给当前container下用户授权。CDB$ROOT中，也可指定container=all，从而对所有打开的PDBs中存在的该用户进行授权。
[oracle@rac19c1 ~]$ sqlplus / as sysdba
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> grant connect to c##usr1;
Grant succeeded.
SQL> colu grantee for a30
SQL> select grantee,con_id from cdb_role_privs where granted_role='CONNECT' and GRANTEE='C##USR1';
GRANTEE CON_ID
------------------------------ ----------
C##USR1 1
SQL> grant resource to c##usr1 container=all;
Grant succeeded.
SQL> select grantee,con_id from cdb_role_privs where granted_role='RESOURCE' and GRANTEE='C##USR1';
GRANTEE CON_ID
------------------------------ ----------
C##USR1 1
C##USR1 3
3.参数修改
CDB$ROOT中修改参数，PDBs会继承该参数值；PDB中进行参数修改，会覆盖掉其从CDB$ROOT继承的该参数的值。
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> alter system set open_cursors=800;
System altered.
SQL> show parameter open_cur
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
open_cursors integer 800
SQL>
SQL>
SQL>
SQL> alter session set container=pdb1;
Session altered.
SQL>
SQL> show parameter open_cur
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
open_cursors integer 800
SQL>
SQL> alter system set open_cursors=1000;
System altered.
SQL> show parameter open_cur
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
open_cursors integer 1000
SQL> conn / as sysdba
Connected.
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> show parameter open_cur
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
open_cursors integer 800
