I keep getting the ORA-12560 error when I try to use either SQL Plus or
SVRMGRL. I have installed Oracle 8.1.5 on a Windows 2003 server .If I
explicitly specify the instance, then I can make the connection, but
otherwise I can't. I have set Oracle_Sid =mydb .
ORA-12560: TNS

rotocol adapter error
D:\>SVRMGRL