这篇文章主要介绍PHP中OCP原则的示例分析，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！1. 什么是“开放-封闭”随着软件系统规模的不断增大，软件系统的维护和修改的复杂性不断
开闭原则（Open Closed Principle）是Java世界里最基础的设计原则，它指导我们如何建立一个稳定的、灵活的系统。 定义： 一个软件实体如类、模块和函数应该对扩展开放，对修改关闭。
11、Which three are true about UNDO data? A) It is used to roll back failed transactions. B) It
13、Which two are true about AWR snapshots? A) They are stored In the SYSAUX tablespace. B) They
12、Which two types of Information can be found in the alert log? A) instance recovery details B
38、Which two are true about data dictionary and dynamic performance views (v$ views)? A) All dat
19、Which two can be backed up by using RMAN when a database Is open in ARCHIVELOG mode, so that me
57、Which two statements are true about dispatchers used by the Oracle shared server? A. Multiple
69、Which is true about unusable indexes? A. Rebuilding an unusable index always requires at least
2、Which two are true about Optimizer Statistics? A) They do not persist across Instance restarts.