How to create a small and simple database using Oracle 11 g and SQL Developer

Question

How can I build a tiny, straightforward database with Oracle 11g and SQL Developer? I'm seeing entirely too many problems, and I can't figure out how to create a straightforward database. For instance:

create database company; 

Caused the following error:

Error starting at line 1 in command:
create database company
Error at Command Line:1 Column:0
Error report:
SQL Error: ORA-01501: CREATE DATABASE failed
ORA-01100: database already mounted
01501. 00000 -  "CREATE DATABASE failed"
*Cause:    An error occurred during create database
*Action:   See accompanying errors.

Answer 1

First off, most other database products do not refer to a database in the same way that Oracle does. A "schema" in Oracle refers to the collection of objects owned by a specific user, although a "database" in MySQL or SQL Server is much more similar to that. In Oracle, a server would typically only have one database on it (but a big server might have several databases on it), and each database would have a variety of schemas. You may only have one database on each server if you are using Oracle's express edition. The Oracle database has already been built if you are able to connect to Oracle with SQL Developer.

Using Oracle terminology, assuming you actually want to establish a schema rather than a database, you would create the user.

CREATE USER company
  IDENTIFIED BY <<password>>
  DEFAULT TABLESPACE <<tablespace to use for objects by default>>
  TEMPORARY TABLESPACE <<temporary tablespace to use>>

You would then assign the user whatever privileges you wanted:

GRANT CREATE SESSION TO company;
GRANT CREATE TABLE TO company;
GRANT CREATE VIEW TO company;
...

Once that is done, you can connect to the (existing) database as COMPANY and create objects in the COMPANY schema.