基本环境：
机器1： 192.168.56.102 用作dblink的使用者（create database link 语句在此执行）
机器2： 192.168.56.103 用作dblink的源
步骤1：机器2上，启动数据库(oracle_sid:orcl)，启动listener。
步骤2：机器1上，通过运行netca 或者手动修改tnsnames.ora文件，建立到机器1的本地服务名：
生成的tnsnames.ora 文件如下：
[oracle@localhost admin]$ cat tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
REMOTE_ORCL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.103)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = orcl)
)
)
ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)
[oracle@localhost admin]$
此处建立的连接到机器2的本地服务名为 remote_orcl。
步骤3：机器1上，给予用户scott（将来从此用户来作为dblink的访问者）建立public dblink的权限。
SQL> alter user scott account unlock;
User altered.
SQL> alter user scott identified by scott;
User altered.
SQL>
SQL> grant CREATE PUBLIC DATABASE LINK, DROP PUBLIC DATABASE LINK to scott;
Grant succeeded.
SQL>
步骤4：建立dblink，通过dblink，可以访问机器2上的 hr schema。
[oracle@localhost ~]$ sqlplus scott/scott
SQL*Plus: Release 11.2.0.1.0 Production on Fri Mar 14 11:26:35 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
SQL> create public database link remote_mydb connect to hr identified by hr using 'remote_orcl';
Database link created.
SQL>
此处建立的dblink名称为 remote_mydb。连接到机器2的hr schema，identified by hr 中的hr，是机器2上hr用户的口令。
步骤5：在机器1上，scott用户通过 dblink 访问机器2的hr schema的表：
SQL> select * from hr.countries@remote_mydb;
CO COUNTRY_NAME REGION_ID
-- ---------------------------------------- ----------
AR Argentina 2
AU Australia 3
BE Belgium 1
BR Brazil 2
CA Canada 2
CH Switzerland 1
CN China 3
DE Germany 1
DK Denmark 1
EG Egypt 4
FR France 1
...
25 rows selected.
SQL>