Problem Environment : Windows R2 64-bit , Oracle 11.2.0.4, multiple instances .
In this case,
Sqlplus "/as sysdba"
The default login is the one that is installed behind the system, and theoracle_sid configuration is the registry:
Windows default oracle_sid location:
Hkey_local_machine\software\oracle\key_oradb11g_home1
Oracle_sid
If you want to switch to another Oracle switch instance,
Most of the methods found online are: Reset the oracle_sid in the cmd window ,
Set Oracle_sid=xxx
Sqlplus "/as sysdba"
This method is available under Win2003. But not in my environment, still into the default instance.
Workaround: In Sqlplus specified in the command Oracle_sid .
Sqlplus "/as sysdba" into the default Windows default oracle_sid instance
Sqlplus "/@dbsch as SYSDBA", enter the specified oracle_sid instance
Sqlplus "/@ldj as SYSDBA"
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Win2012,oracle11g,sqlplus How to switch instances