dblink

三. 创建DBLINK的方法：
    1. create public database link dblink
       connect to totalplant identified by totalplant
       using '(DESCRIPTION =
                (ADDRESS_LIST =
                  (ADDRESS = (PROTOCOL = TCP)(HOST = LOCALHOST)(PORT = 1521))
                )
                (CONNECT_DATA =
                  (SERVICE_NAME = prd.gdc)
                )
              )';
        语法解释：create public database link DBLINK名字(自己随便起)
                  connect to 用户名 identified by 密码
                  using '(DESCRIPTION =
                            (ADDRESS_LIST =
                              (ADDRESS = (PROTOCOL = TCP)(HOST = 要连接的数据库所在服务器的IP地址)(PORT = 1521))
                            )
                            (CONNECT_DATA =
                              (SERVICE_NAME = 要连接的数据库的在本地的服务名(即要连接的数据库的SID))
                            )
                          )';
     2. 如果创建private的DBLINK
        create database link dblink
        connect to totalplant identified by totalplant
        using '(DESCRIPTION =
                (ADDRESS_LIST =
                  (ADDRESS = (PROTOCOL = TCP)(HOST = LOCALHOST)(PORT = 1521))
                )
                (CONNECT_DATA =
                  (SERVICE_NAME = prd.gdc)
                )
              )';                       
四. 连接成功后从所连接的数据库中取数的方法：
     1. select * from tbl_ost_notebook@dblink;
     说明：只需在表名的后面加上"@DBLINK名字"即可。   
五. 在当前数据库下查看所有的DBLINK的方法：
     1. select * from dba_db_links;    
六. 删除当前数据库下的一个指定的DBLINK的方法：
     1. 如果创建的是一个public的DBLINK，删除时需要用
        drop public database link dblink;
     2. 如果创建的是一个private的DBLINK，删除时需要用
        drop database link dblink;
     说明：drop public database link DBLINK名字;    
七. 查看当前数据库的全局数据库名的方法：
     1. select * from global_name;  
八. 查看当前用户具有哪些针对DBLINK的权限的方法：
     1. SELECT DISTINCT PRIVILEGE AS "Database Link Privileges"
        FROM ROLE_SYS_PRIVS
        WHERE PRIVILEGE IN ( 'CREATE SESSION','CREATE DATABASE LINK',
                             'CREATE PUBLIC DATABASE LINK');   
八. 参考资料：
           http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14231/ds_admin.htm#i1008271