nstantclient-basic-nt-12.1.0.1.0\instantclient_12_1下面新建NETWORK文件夹，NETWORK下新建ADMIN文件夹，ADMIN下新建tnsnames.ora文件，内容
ORCL=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = ORCL)
)
)
原文：http://www.cnblogs.com/gaobing/p/3896333.html