How to create a database

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First of all you need an instance, please refer to how to create an instance

Suppose db name is reposit, $ORACLE_BASE is /opt/ora9, init parameter undo_tablespace='UNDOTBS1'

Character set
#Remember that a character set of a database can be determined using:
select value from NLS_DATABASE_PARAMETERS where parameter = 'NLS_CHARACTERSET'

Bring database to nomount state, and issue

CREATE DATABASE reposit
USER SYS IDENTIFIED BY mypassword
USER SYSTEM IDENTIFIED BY mypassword
LOGFILE GROUP 1 ('/opt/ora9/oradata/reposit/redo01.log') SIZE 100M,
GROUP 2 ('/opt/ora9/oradata/reposit/redo02.log') SIZE 100M,
GROUP 3 ('/opt/ora9/oradata/reposit/redo03.log') SIZE 100M
MAXLOGFILES 10
MAXLOGMEMBERS 5
MAXLOGHISTORY 1
MAXDATAFILES 30
MAXINSTANCES 1
CHARACTER SET al32utf8 #or WE8MSWIN1252
NATIONAL CHARACTER SET al16utf16
DATAFILE '/opt/ora9/oradata/reposit/system01.dbf' SIZE 325M REUSE
EXTENT MANAGEMENT LOCAL
DEFAULT TEMPORARY TABLESPACE tempts1 TEMPFILE '/opt/ora9/oradata/reposit/temp01.dbf' SIZE 20M REUSE
UNDO TABLESPACE UNDOTBS1
DATAFILE '/opt/ora9/oradata/reposit/undotbs01.dbf'
SIZE 200M REUSE AUTOEXTEND ON NEXT 5120K MAXSIZE UNLIMITED;

CASE SENSITIVE:

Remember that database name, in this example reposit, must have the same case of SID_NAME entry in listener.ora, in orapw and init file

Create Dictionary Views

as sys launch:
nohup sqlplus "/ as sysdba" @?/rdbms/admin/catalog.sql &
nohup sqlplus "/ as sysdba" @?/rdbms/admin/catproc.sql &
nohup sqlplus "/ as sysdba" @?/rdbms/admin/catblock.sql &
#install text indexes,                          <ctxsys pwd> <tbs>
  nohup sqlplus "/ as sysdba" @?/ctx/admin/catctx.sql ctxsys context temp nolock &
  #install default localized option US
  sqlplus ctxsys/ctxsys @?/ctx/admin/defaults/drdefus.sql
#caution, be sure to view this log, init.ora may be underestimated
nohup sqlplus "/ as sysdba" @?/javavm/install/initjvm.sql &

#Optional install Web Services

as system launch the script to permit connectivity with Oracle7 versions:
@?/sqlplus/admin/pupbld.sql

I recommend to sql an ALTER DATABASE FORCE LOGGING;
alter database archivelog; #if needed

Now we add a tablespace for user data
sql>create tablespace "USER" logging datafile '/opt/ora9/oradata/reposit/USER.dbf' size 5M extent management local segment space management auto;

sql>alter database datafile '/opt/ora9/oradata/reposit/USER.dbf' autoextend on next 1M;
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