How to access multiple database present in single instance

Hi Team,
In oracle 11.2, can there be multiple databases in an instance??? In one of our environment, I could see multiple databases in an instance. Could you please help me in giving the data dictionary or query to access those databases?
Actually, querying v$database, I could see only one database which is same as instance name. But in inventory, there are multiple database in an instance?
I am still not exactly clear about this. Can someone help me with this?
Thanks!
Vidhya

In Oracle one instance manages one (1) database. A database consists of multiple *schemas*.
Other vendors erroneously call a schema 'database'.
So, no, you didn't see multiple databases.
There is also one datadictionary, consisting of a set of views.
All views beginning with dba_ list the entire database, all schemas.
All views beginning with all_ list the objects you have access to.
All views beginning with user_ list your own objects.
The view DICT show you the contents of the datadictionary.
Oracle also has online documentation at http://docs.oracle.com
From your question it is clear you should read the document called the 'Oracle Concepts Manual'.
You can find all documentation for 11gR2 here Oracle Database Online Documentation 11g Release 2 (11.2)
Too many people here don't make any effort to read it. This is probably the reason why you got no response.
Sybrand Bakker
Senior Oracle DBA

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