ORA-01012: not logged on Issue

Today I have received an unexpected error which I never got before today.

I am able to login into the database server as sysdba but not able to put or execute any query. It is showing the database instance connected but when I used to start up the database it is throwing me an error:

ORA-01081: cannot start already-running ORACLE - shut it down first.

 

Every time I tried to  execute any query it is giving me the error. 

Solution: 

First I tried to shutdown the database and again reopen so I used the command shutdown immediate which is the best approach to shutdown the database but it is not worked for me.

 sql> shutdown immediate;   ---> this command not worked for me and again throw me the error.

Lastly I used the command shutdown abort

sql>shutdown abort;

   Oracle Instance shutdown

 Dont know there are so many alternatives are present but this option workout for me.

Hope it worked in your case also.

Have Fun !!!