连接到oracle时出现以下错误:
C:\Users\nikhilgupta>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Sun Jan 19 21:27:54 2014
Copyright (c) 1982, 2010, Oracle. All rights reserved.
ERROR:
ORA-12560: TNS:protocol adapter error
Enter user-name: nikhil
Enter password:
ERROR:
ORA-12560: TNS:protocol adapter error
请帮助。