Which three statements are true about the stages of database startup? (Choose three.)
A. Data files and redo log files can be renamed at the MOUNT stage.
B. Control files are required to bring the database to the NOMOUNT stage.
C. Data files and online redo log files are checked for consistency while opening the database.
D. Data files and redo log files are made available to users at the OPEN stage.
E. Control files are read at the OPEN stage for the location of data files.
Answer: ACD
oracle启动时：nomount(获取参数文件)→mount(通过参数文件获取控制文件目录)→open(根据控制文件中记录的数据文件、日志文件的位置信息、检查点信息决定是否能启动数据库)
重命名控制文件、删除用户 、删除表空间要在OPEN状态下;
配置归档模式、重命名数据文件、启用或禁用 redo 日志归档选项、执行完整的数据库恢复需要在MOUNT状态下
多路备份control要在pfile中修改参数，必须shutdown
B应该在MOUNT下，E不仅需要位置还要检查点信息