Oracle Trouble shooting

 When I am trying to sign in to Oracle 11g  in windows xp , I am getting the error  'ORA-12560: TNS:protocol adapter error'

Solution:
Try1:
set local=databasename
For example, if name of database is orcl, command will be
C:\ set local = ORCL

Then log in to sqlplus 
C:\ sqlplus / as sysdba
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Try 2

If try1 does not work,

In command prompt do the following:
C:\ set ORACLE_SID =  databasename
 Important:  The database name has to be in uppercase letters. 

For example, if name of database is orcl, command will be
C:\ set ORACLE_SID = ORCL

Then log in to sqlplus 
C:\ sqlplus / as sysdba

SQL*Plus: Release 11.1.0.6.0 - Production on Sun Jun 20 00:06:58 2010


Copyright (c) 1982, 2007, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

Now you are connected to the database.
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