How to modify a database?

Question

Hi forum members, I recently installed oracle10g on solaris 10 , and I could create a test database called solaris, but I could'nt create a new table for that database, Indeed I don't know how to open the database, thanks for your help I'm new in oracle and solaris as well.
I tried this but I couldn't modify the database
$ ./sqlplus /nolog
SQL*Plus: Release 10.1.0.3.0 - Production on Tue Nov 29 16:07:22 2005
Copyright (c) 1982, 2004, Oracle. All rights reserved.
SQL> CONNECT / AS SYSDBA
Connected.
SQL> STARTUP MOUNT
ORA-01081: cannot start already-running ORACLE - shut it down first
SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> STARTUP MOUNT
ORACLE instance started.
Total System Global Area 167772160 bytes
Fixed Size 778212 bytes
Variable Size 61874204 bytes
Database Buffers 104857600 bytes
Redo Buffers 262144 bytes
Database mounted.
SQL> CREATE TABLE "usuario" ("id" NUMERIC,"nombre" VARCHAR(30));
CREATE TABLE "usuario" ("id" NUMERIC,"nombre" VARCHAR(30))
ERROR at line 1:
ORA-01109: database not open
thanks in advance

Answer 1

You really need to get caught up on some basics. I encourage you to pick up the O'Reilly book titled 'Oracle Essentials' (see http://oracle.oreilly.com) to get up to speed. And then plan on spending some time either in the 2-day DBA or Oracle Concepts documentation.
To give you a bit of a start -
An Oracle database is a bunch of files. The database is controlled by an Oracle Instance. The instance is started (attached to the database) and stopped. In Windows the instance is a [Control Panel] service.
A listener can be started [and stopped] to monitor the network for requests. It is also a service. If it is not started, the instance will not respond to any network requests but WILL respond to SQLPlus requests by the same userid that installed the database and software.
You use the internal userid called SYS to do basic things like start and stop the instance. The SYS userid should never be used for anything else (there are exceptions to every rule, but...). Most newbies ignore this advice until they blow up their first database.
You can use DBA userid such as SYSTEM to manage the database to do things like add/manage users, add/manage schemas and add/manage tablespaces. A DBA userid should only be used for managing the database, not for owning tables and not for application work. Most newbies ignore this advice until they cripple up their first database.
User:
A userid should be created for each user - and each schema (see next section). You create it using sqlplus commands, usually run by the SYSTEM user
CREATE USER username IDENTIFIED BY password ACCOUNT UNLOCK
DEFAULT TABLESPACE USERS TEMPORARY TABLESPACE TEMP;
and give it privileges such as accessing the database and storing data by
ALTER USER username QUOTA UNLIMITED ON USERS;
GRANT CONNECT TO username;
Schema:
A schema is a special user that also has resource capability and ability to create and manage objects such as tables. There are many kinds of objects and ideally you should give permission to create/manage only those objects that are needed, such as
GRANT CREATE TABLE TO username; -- this makes is a schema.
Cheating - you can grant the resource role to the user which provides all the GRANTS for most objects.
GRANT RESOURCE TO username;
I call it cheating, because few actually look at the role and fewer realize how much capability is given by the resource role. It's pretty darned close to opening up security holes. Oh well ...
People who have had time with other RDBMSs such as SQL Server may view an Oracle Schema as roughly the same as a SQL Server (or other) Database.
Tablespace:
A tablespace is like a disk to Oracle - you can store things such as [many] tables and indexes in a tablespace. A tablespace is made of [one or more] operating system files. A number of files can be used in a tablespace to get around things like the 2GB limit that many operating systems have for typical files.
There are a bunch of tablespaces:
SYSTEM is for keeping the internal data dictionary and you should avoid using it for anything as filling it up will cause the database to stop.
SYSAUX is for Oracle's options and features and you should avoid using it as filling it up causes major pain. SYSAUX was introduced in 10g.
TEMP is used for sorting and other internal stuff. Do not let it autoextend otherwise it will grow forever. If you limit the size the area will be reused even though it appears to be busy.
UNDO/ROLLBACK is used for internal stuff such as recovering the original data if you cancel a transaction. Keep away from it other than to make it bigger. It's you friend - feed it properly and you can recover from data mistakes you made a few days ago.
Regular tablespaces are what's left - that's where your tables and indexes go (remember the DEFAULT TABLESPACE clause in create user???)
CREATING TABLES ...
Simplest form: as a new userid,
CREATE TABLE name_of_table (
column_name datatype_and_size,
another_column datatype_and_size ...
example:
CREATE TABLE test ( test1 date, test2 number, test3 varchar2(25));
then use it
INSERT INTO test VALUES (
to_date('Feb 13, 1987 09:14:56', 'Mon DD, YYYY HH:MI:SS'),
42,
'A test string');
SELECT test3 from test;
Oracle provides a few demo userids such as OE, HR, SH, IX & PM. Go to the documentation for your version of the database at http://docs.oracle.com and pull up the document titled 'Sample Schemas'. They are to help you learn about Oracle complete with data, and are usually loaded by default into new databases. A number of the examples and tutorials at Oracle By Exmaple (from http://otn.oracle.com >> Training menu >> Oracle By Example) use these schemas.