ORA-12560: TNS: protocol adapter error

PROBLEM:

   Login as sqlplus / as sysdba .

              ORA-12560: TNS: protocol adapter error.

REASON:

 1. Tnslistener not running or not available.

              2. Oracle Instance not created.

              3. Oracle SID not set.

              4. Oracle service is not started

SOLUTION:

          In Oracle 11g db home tnslistener not available in the Application. You are required to install Oracle 11g db client Application. Go to custom installation and select the listener and follow the step finish installation.

1. Create the trace folder [ E:\oradata\hcsys].

2. Please check whether Environment variables are set.

3. Choose a Database Administrator Authentication [OS Authentication in SQLNET.ORA used here].

4. Create init.ora file.

5. Type following Command for creating oracle service instance.

>oradim -NEW -SID HCSYS -STARTMODE auto

6. Now you can login as sqlplus / as sysdba.