CentOS 7
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Oracle Database 12c : Create Database
Create a Database.
[1] Login with the oracle admin user and input a command "dbca" like follows.
[oracle@dlp ~]$ dbca

[2] Select "Create Database" and go next.
[3] On this example, select "Advanced Mode" and go next.
[4] This example selects "General Purpose ***" and go next.
[5] Set Grobal Database name and SID like follows. Input any one you like.
[6] This example goes next with keeping default.
[7] Set passwords. Please set a password for a user for security.
[8] Configure Listener. On this example, keep default and go next.
[9] Configure Storage settings. On this example, keep default and go next.
[10] Configure sample schema and scripts. If you'd like to add them, Set them.
[11] Configure memory settings. After setting, go to next tab.
[12] Specify max processes.
[13] Set Character setting.
[14] Select a connection mode. If your server does not have many clients, Select Dedicated server mode. If your server has many clients, Select Shared server mode.
[15] Go next.
[16] Configuration completed. Click "Finish" button to finish.
[17] Database creation starts.
[18] After completing to create a database, Click "Close" to finish.
[19] Add Database SID to the environment variables.
[oracle@dlp ~]$
vi /etc/oratab
# change like follows

[oracle@dlp ~]$
vi ~/.bash_profile
# add to the end

export ORACLE_SID=dlp