18C 建库 ORA-12754 错误的解决办法
[oracle@dg18c ~]$ sqlplus / as sysdba
SQL> startup nomount;
ORA-12754: Feature 'startup' is disabled due to missing capability 'Runtime Environment'.18C 建库时，会遭遇 ORA-12754 错误，感谢 @双鱼卡农 的指导，
初始化参数中增加 _exadata_feature_on=true 即可解决问题。
剩下的就比较简单了，通过OMF的方式，直接create database即可：
CREATE DATABASE skydb
USER SYS IDENTIFIED BY oracle
USER SYSTEM IDENTIFIED BY oracle
EXTENT MANAGEMENT LOCAL
DEFAULT TEMPORARY TABLESPACE temp
UNDO TABLESPACE undotbs1
DEFAULT TABLESPACE users;