How to block external connections for an Oracle database

One of the key differences between these platforms is that a database in MySQL is a schema in Oracle. Since a schema in Oracle is also a user, the command you are looking for is CREATE USER. I highly recommend that you read the Oracle Concepts Guide before continuing. You may also find this documentation on MySQL>>Oracle migrations using SQL Developer useful. Here is the part relevant to your situation:

When migrating MySQL databases to Oracle, SQL Developer maps each MySQL database to a tablespace in Oracle. Database objects, such as tables, indexes and views are stored in the respective tablespaces and are referenced from the Oracle schema for the user that owns them.

From the error message perspective, the salient part to pull out is "ORA-01100: database already mounted". This indicates that a database has already been created and mounted. It may also be open. Here is an example reproducing your issue, opening the database (which may not be necessary if it is already open) and creating a django user.

SQL> create database django;
create database django
*
ERROR at line 1:
ORA-01501: CREATE DATABASE failed
ORA-01100: database already mounted


SQL> SELECT status FROM v$instance;

STATUS
------------
MOUNTED

SQL> ALTER DATABASE OPEN;

Database altered.

SQL> SELECT status FROM v$instance;

STATUS
------------
OPEN

SQL> create database django;
create database django
*
ERROR at line 1:
ORA-01501: CREATE DATABASE failed
ORA-01100: database already mounted


SQL> CREATE USER django IDENTIFIED BY "No More ORA-001100.";

User created.

You should also assign permissions and create a django tablespace setting it as the default tablespace for django.

I had no problems with a VirtualBox 4.14 Windows 8 preview VM and x64 Oracle 11gR2.

My VM uses 40 GB Hard Disk. While installing it downloaded .Net Framework 3.51 I started with a fresh Windows 8 VM in VirtualBox 4.14 and installed guest additions and run Windows update once. Afterwards I installed Oracle and got the items below on my Start page.

I find the databasefiles of my new database Bk_W8 in C:\app\berndk\oradata\Bk_W8. That is the location I would use for additional tablespaces.

The rest can be done by scripts which can be executed by sqlplus from this machine or from another client and is not Windows 8 specific.

Edit:

By right-clicking on the item on the start page, via advanced | open file location I found the path to the start menu:

C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Oracle - OraDb11g_home1\Konfigurations- und Migrations-Tools

I guess you will find

C:\ProgramData\Microsoft\Windows\Start Menu\Programs

the other is specific for a German Oracle installation.

To get access to the hidden C:\ProgramData folder see this link showing how to access folder options in Windows 8

Final hint: My VM currently uses 23 GB for the virtual hard disk.

OK I'm going to retry this with the Oracle Database Express Edition 11g Release 2 (September 2011). But that takes some time.

Installation done: The is the Web interface of Oracle 11g XE in Windows 8

For the question of creating addition databaseinstances: from this question on SO we learn, that it is not possible.

Creating tablespaces and users can be done using sqlplus. Which I found at C:\oraclexe\app\oracle\product\11.2.0\server\bin\sqlplus.exe.

Now going to remove that Virtual machine. I think there are better ways to learn Oracle.