[oracle@chen admin]$ pwd
/u01/app/oracle/product/11.2.0/network/admin


[oracle@chen admin]$ vim tnsnames.ora 
222=
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.222)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = aaa)
    )
  )


[oracle@chen admin]$ tnsping 222

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 23-AUG-2014 23:51:27
Copyright (c) 1997, 2009, Oracle.  All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.222)(PORT = 
1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = aaa)))
OK (10 msec)


[oracle@chen ~]$ sqlplus 

SQL*Plus: Release 11.2.0.1.0 Production on Sat Aug 23 23:51:37 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Enter user-name: chen/chen@201

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options

SQL> show user
USER is "CHEN"
SQL> select * from tab;

TNAME                          TABTYPE  CLUSTERID
------------------------------ ------- ----------
CHEN_T1                        TABLE

SQL> select * from chen_t1;
        ID
----------
         1
         2

SQL> select name from v$database;
NAME
---------
AAA


SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

[oracle@chen ~]$ sqlplus    

SQL*Plus: Release 11.2.0.1.0 Production on Sun Aug 24 00:18:51 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Enter user-name: /as sysdba

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> grant create public database link,create database link to scott;
Grant succeeded.

SQL> grant drop public database link to scott;
Grant succeeded.

SQL> conn scott/tiger
Connected.

SQL> create public database link aaa_link connect to chen identified by "chen" using '222';
Database link created.

SQL> select * from chen_t1@aaa_link;
        ID
----------
         1
         2

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