Creating a New User & Schema

Question

This is the 1st time I've logged into the Oracle 11g database as 'sysdba' using the SQL*Plus client. I'm trying to learn how Oracle creates objects and users but I can't find any info that helps me break down / understand what I'm missing. I guess this is a warning and just let you all know that I'm a PostgreSQL guy. In PostgreSQL, we create roles, not users. So now that I'm logged into Oracle 11g, I created a regular test user:
CREATE USER carlos IDENTIFIED BY doesntknowsql;
Then I need to grant session access to this user so:
GRANT CREATE SESSION
TO carlos;
So this now gives me a user named 'carlos' with the grants to login, correct?
My next question or confusion in being new to Oracle is the way it handles a 'database' and now this word is a little confusing but generally I can't just write a SQL statement to CREATE DATABASE test OWNER carlos;
I've learned that in Oracle, you create a user and every user has it's own schema or container that is associated with that particular user or group role assigned to it. Is this accurate or close enough? If not, could someone please clarify for me to help my confusion?
So I'm trying to understand how my newly created user 'carlos' can connect to Oracle 11g using SQL*Plus and how he can then create a table of sorts to start writing data into it. I guess I'm missing something and I'm reading the documentation but there's so much information!
Thanks for any help!!!

Answer 1

When I connect to the database as 'carlos', am I in a specific schema or named work space? When you log in to the database as carlos, your current_schema is set to CARLOS, yes. There are rare cases where it makes sense to change your current_schema but for the moment, assume that's not changable. If you log in as CARLOS, you're working with CARLOS's schema unless you explicitly qualify the object name with a schema name. So
SELECT * FROM testis going to implicitly query the TEST table in the CARLOS schema while
SELECT * FROM bob.testis going to explicitly query the TEST table in the BOB schema.
I tried logging in and creating a table but I'm obviously missing something:Actually, we probably missed something.
In a default 11.2 install, what you posted should work and a table TEST should be created in the CARLOS schema
SQL> conn / as sysdba
Connected.
SQL> create user carlos identified by letmein;
User created.
SQL> grant create session to carlos;
Grant succeeded.
SQL> grant create table to carlos;
Grant succeeded.
SQL> conn carlos/letmein
Connected.
SQL> create table test (
  2    id integer primary key,
  3    name varchar2(100) not null
  4  );
Table created.but when you try to insert a row, you'll get an error because you haven't been granted any quota in the tablespace you created the table in
SQL> insert into test values( 1, 'Justin' );
insert into test values( 1, 'Justin' )
ERROR at line 1:
ORA-01950: no privileges on tablespace 'USERS'In earlier versions of Oracle, or in 11.2 databases where deferred segment creation is not enabled, you would get an error creating the table. You can fix that by granting the user quota on whatever tablespace(s) you want him to use. For example
SQL> conn / as sysdba
Connected.
SQL> alter user carlos
  2    quota 10M on users;
User altered.gives the CARLOS user privileges to use 10 MB of space in the USERS tablespace. Once you do that, you'll be able to insert the row
SQL> conn carlos/letmein
Connected.
SQL> insert into test values( 1, 'Justin' );
1 row created.If you don't care about how much space CARLOS uses or what tablespaces he uses, you can
GRANT unlimited tablespace TO carlosJustin