Can't access an ORACLE db on Windows via setting %ORACLE_SID%

Question

Hello!
I'm pretty new to ORACLE on Windows (I'm a UNIX person), so I would appreciate any help I can get! I have two ORACLE 11.2.0.1 databases on a Windows 2008 R2 server. One of the databases crashed due to too many archive logs in flash recovery area (the RMAN backup I put together was never scheduled by the sysadmin). I removed all old archive logs and am trying to log into the database to clean it up but I can't get in. Changing %ORACLE_SID% doesn't seem to work:
C:\Users\kcoachman>set %ORACLE_SID%=test <== this is the database which is up with no issues
C:\Users\kcoachman>set %ORACLE_SID%
%ORACLE_SID%=test
C:\Users\kcoachman>set %ORACLE_HOME%
%ORACLE_HOME%=F:\app\wcadmin\product\11.2.0\dbhome_1
C:\Users\kcoachman>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Thu Feb 28 12:20:48 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Release 11.2.0.1.0 - 64bit Production
SQL> select name from v$database;
NAME
TEST
SQL> exit
Disconnected from Oracle Database 11g Release 11.2.0.1.0 - 64bit Production
C:\Users\kcoachman>set %ORACLE_SID%=abat <== this is the database which crashed
C:\Users\kcoachman>set %ORACLE_SID%
%ORACLE_SID%=abat
C:\Users\kcoachman>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Thu Feb 28 12:21:07 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Release 11.2.0.1.0 - 64bit Production
SQL> select name from v$database;
NAME
TEST <== what? I'm still in TEST!
SQL> exit
Disconnected from Oracle Database 11g Release 11.2.0.1.0 - 64bit Production
Changing %ORACLE_SID% worked fine before the database crashed. Also I have another server with 3 ORACLE Databases, no problems going from one database to another via changing %ORACLE_SID%... Has anyone seen this before and how do I get into the database to fix it?
Thank you!
Katya

Answer 1

On Windows, you don't set ORACLE_HOME as environment variable directly. You set PATH and rest of env is setup via oracle.key file and Registry variables/values.
To "see" this, open a new command window, run sqlplus (found via PATH setting, or explicit path in command line), and check %oracle_home% and %oracle_sid% inside sqlplus. E.g. using @[[%oracle_sid%]].
For the attempt to set ORACLE_SID for the "second" instance, within the same Home. You actually set a variable named %ORACLE_SID%. Which can be tricky, if not dangerous (allowing % in variable names, that is).
C:\>set ora
Environment variable ora not defined
C:\>set %ora
Environment variable %ora not defined
C:\>set | findstr /i "ora"
C:\>set %ora%=test1
C:\>set ora=test2
C:\>set | findstr /i "ora"
%ora%=test1
ora=test2
C:\>set %ora%=test3
C:\>set | findstr /i "ora"
%ora%=test1
ora=test2
C:\>set | findstr /i "test"
%ora%=test1
ora=test2
test2=test3Edited by: orafad on Feb 28, 2013 10:41 PM
Edited by: orafad on Feb 28, 2013 10:47 PM