oracke创建db link

-- Create database link 
create public database link test_link
  connect to 用户名 identified by 密码
  using '
 (DESCRIPTION =
   (ADDRESS = (PROTOCOL = TCP)(HOST = ip地址)(PORT = 端口))
   (CONNECT_DATA =
     (SERVER = DEDICATED)
     (SERVICE_NAME = 服务名)
   )
 )';