C:\Users\Administrator>echo %ORACLE_HOME%
C:\app\Administrator\virtual\product\12.2.0\dbhome_2
C:\Users\Administrator>sqlplus / as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on 星期六 12月 16 09:11:50 2017

Copyright (c) 1982, 2016, Oracle. All rights reserved.

连接到:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL> show pdbs

CON_ID CON_NAME                       OPEN MODE  RESTRICTED

     2 PDB$SEED                       READ ONLY  NO
     3 PDBTEST                        READ WRITE NO
     4 CLONEPDB_PLUG                  MOUNTED

SQL> alter pluggable database clonepdb_plug open;

插接式数据库已变更。

SQL> show pdbs

CON_ID CON_NAME                       OPEN MODE  RESTRICTED

     2 PDB$SEED                       READ ONLY  NO
     3 PDBTEST                        READ WRITE NO                                                
     4 CLONEPDB_PLUG                  READ WRITE NO              

SQL> alter session set container=CLONEPDB_PLUG;

会话已更改。
SQL> show user
USER 为 "SYS"
SQL> show con_name;
CON_NAME ------------------------------
CLONEPDB_PLUG
SQL> @%ORACLE_HOME%\rdbms\admin\utlsamplpdb.sql
从 Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production 断开
C:\Users\Administrator>sqlplus / as sysdba
SQL*Plus: Release 12.2.0.1.0 Production on 星期六 12月 16 09:22:07 2017
Copyright (c) 1982, 2016, Oracle. All rights reserved.

连接到:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
SQL> alter session set container=CLONEPDB_PLUG;

会话已更改。

SQL> select username from dba_users where username = 'SCOTT';

USERNAME

SCOTT

SQL> conn scott/tiger@CLONEPDB_PLUG 已连接。
SQL> select table_name from user_tables;

TABLE_NAME

DEPT
EMP
BONUS
SALGRADE

深入一步
C:\Users\Administrator>sqlplus/ as sysdba
SQL*Plus: Release 12.2.0.1.0 Production on 星期六 12月 16 10:13:16 2017
Copyright (c) 1982, 2016, Oracle. All rights reserved.

连接到:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL> show pdbs

CON_ID CON_NAME                       OPEN MODE  RESTRICTED

     2 PDB$SEED                       READ ONLY  NO                                                                        
     3 PDBTEST                        READ WRITE NO
     4 CLONEPDB_PLUG                  READ WRITE NO

SQL> alter session set container=CLONEPDB_PLUG;

会话已更改。
SQL> -- Grant/Revoke system privileges
SQL> grant create session to ROLE_APPPOSERP;

授权成功。

SQL> grant delete any table to ROLE_APPPOSERP;

授权成功。

SQL> grant execute any procedure to ROLE_APPPOSERP;

授权成功。

SQL> grant insert any table to ROLE_APPPOSERP;

授权成功。

SQL> grant select any sequence to ROLE_APPPOSERP;

授权成功。

SQL> grant select any table to ROLE_APPPOSERP;

授权成功。

SQL> grant update any table to ROLE_APPPOSERP;

授权成功。
SQL> create user DBLINKUSR
2 identified by DBLINKUSR
3 profile DEFAULT;
用户已创建。

SQL> grant role_appposerp to DBLINKUSR;

授权成功。

SQL> alter session set container=pdbtest;

会话已更改。
SQL> create database link
2 CLONEPDB_PLUG connect to DBLINKUSR identified by DBLINKUSR
3 using 'CLONEPDB_PLUG';
数据库链接已创建。
SQL> set wrap off
SQL> set linesize 200
SQL> select * from dual@CLONEPDB_PLUG;
DU

X

SQL> select * from dba_db_links;

OWNER DB_LINK USERNAME HOST CREATED HIDDEN

SYS SYS_HUB SEEDDATA 2017/3/8 16 NO
SYS CLONEPDB_PLUG DBLINKUSR CLONEPDB_PLUG 2017/12/16 NO
PUBLIC DBMS_CLRDBLINK ORACLR_CONNECTION_DATA 2017/12/13 NO
SQL> select * from link$;

OWNER# NAME                                                                             CTIME       HOST                                                                             USERID                                                                           PASSWORD                                                                               FLAG AUTHUSR                                                                          AUTHPWD                                                                          PASSWORDX                                                                        AUTHPWDX

     0 SYS_HUB                                                                          2017/3/8 16 SEEDDATA                                                                                                                                                                                                                                                    0                                                                                                                                                                                                                                                    
     0 CLONEPDB_PLUG                                                                    2017/12/16  CLONEPDB_PLUG                                                                    DBLINKUSR                                                                                                                                                                  2                                                                                                                                                                   0706B6180908B91436DD15579A9716C7AA59A171BE0F860141B44815E4A93536B3ECE15A339EB407 
     1 DBMS_CLRDBLINK                                                                   2017/12/13  ORACLR_CONNECTION_DATA                                                                                                                                                                                                                                      0                                                                                                                                                                                                                                                    

SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ------------------------------ ---------- ----------
3 PDBTEST READ WRITE NO SQL> create public synonym emp for scott.emp@CLONEPDB_PLUG;

同义词已创建。

SQL> desc emp
名称 是否为空? 类型

EMPNO
NOT NULL NUMBER(4)
ENAME VARCHAR2(10)
JOB
VARCHAR2(9)
MGR
NUMBER(4)
HIREDATE
DATE
SAL
NUMBER(7,2)
COMM
NUMBER(7,2)
DEPTNO
NUMBER(2)
SQL> select * from dba_synonyms where SYNONYM_NAME='EMP';

OWNER SYNONYM_NAME TABLE_OWNER TABLE_NAME DB_LINK ORIGIN_CON_ID

PUBLIC EMP SCOTT EMP CLONEPDB_PLUG 3
SQL> create synonym scottemp for scott.emp@CLONEPDB_PLUG;

同义词已创建。
SQL> select * from dba_synonyms where SYNONYM_NAME='SCOTTEMP';

OWNER SYNONYM_NAME TABLE_OWNER TABLE_NAME DB_LINK ORIGIN_CON_ID

SYS SCOTTEMP SCOTT EMP CLONEPDB_PLUG 3
Oracle同义词在数据库链中的作用
数据库链是一个命名的对象，说明一个数据库到另一个数据库的路径，通过其可以实现不同数据库之间的通信。
Create database link 数据库链名 connect to user名 identified by 口令 using ‘Oracle连接串’; 访问对象要通过 object名@数据库链名。同义词在数据库链中的作用就是提供位置透明性。
SQL> drop synonym scottemp
2 ;
同义词已删除。