I created a new database test123 with sample schema option in oracle 11g R2. But I am unable to connect
E:\>sqlplus sys/password
SQL*Plus: Release 11.2.0.1.0 Production on Tue Apr 16 14:32:59 2019
Copyright (c) 1982, 2010, Oracle. All rights reserved.
ERROR:
ORA-12560: TNS:protocol adapter error
I do not have tnsnames.ora as it's my local.
E:\>set oracle_sid = TEST123
E:\>sqlplus scott/tiger
SQL*Plus: Release 11.2.0.1.0 Production on Tue Apr 16 14:44:06 2019
Copyright (c) 1982, 2010, Oracle. All rights reserved.
ERROR:
ORA-12560: TNS:protocol adapter error
Enter user-name: