将客户端的网络服务名更新为abc，如下
abc =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb.robinson.com)(PORT = 1421))
)
(CONNECT_DATA =
(SERVICE_NAME = orcl.robinson.com)
尝试再次连接，可以成功连接，由此可以看出跟网络服务名无关，重要的连接描述信息
Connected.