Creating the Database
Creating a database can either be done manually, using SQL scripts and the CREATE DATABASE command, or with the Database Creation Assistant (DBCA).
Before you can create a database, either manually, or with DBCA, the operating system environment needs to be configured properly, or the database will fail to create correctly.
ORACLE_BASE specifies the topmost directory that will house the Oracle software.
For example: /Oracle or C:\Oracle.
ORACLE_HOME provides the directory where the Oracle software will be installed. Oracle Flexible Architecture suggests that the value of the ORACLE_HOME be set to ORACLE_BASE/product/release#.
For example: /Oracle/product/9_2 or C:\Oracle\database\9_2.
ORACLE_SID is the instance name. This must be unique for all Oracle instances that will be running on the same physical computer.
For example: PROD, DEVELOPMENT, TEST.
Although PATH is not necessarily set only for the Oracle installation but also for ease of navigation and use for users in general both on Unix and Windows platforms, it is important that portions of your path be set to allow for efficient searches for the executables (such as SQL*Plus). Most particularly, it is important for your path to include the ORACLE_HOME/bin directory.
ORA_NLS33 is an optionally set variable that is required when you are going to be creating a database with a character set other than US7ASCII. It is suggested that this point to a subdirectory of the ORACLE_HOME.
For example: ORACLE_HOME/nls/data or ORACLE_HOME\nls\data.
LD_LIBRARY_PATH specifies the directory for operating system and Oracle library files associated with the Oracle instance.
For example: ORACLE_HOME/lib or ORACLE_HOME\lib.