Which is the correct way to connect to both the target database and the recovery catalog from the RMAN command line？（）
Assume that the target database is called ORCL and that the recovery catalog database is called RCAT. Also assume that the recovery-catalog owner is called RCAT_OWN. Assume the environment is configured for the ORCL database. 

单项选择题How can you reverse the effects of an ALTER DISKGROUP ... DROP DISK command if it has alreadycompleted?（）

A. Issue the ALTER DISKGROUP ... ADD DISK command.
B. Issue the ALTER DISKGROUP ... UNDROP DISKS command.
C. Issue the ALTER DISKGROUP ... DROP DISK CANCEL command.
D. Retrieve the disk from the Recycle Bin after the operation completes

单项选择题How can you reverse the effects of an ALTER DISKGROUP ... DROP DISK command if it has not yetcompleted?（）

A. Issue the ALTER DISKGROUP ... ADD DISK command.
B. Issue the ALTER DISKGROUP ... UNDROP DISKS command.
C. Issue the ALTER DISKGROUP ... DROP DISK CANCEL command.
D. Retrieve the disk from the Recycle Bin after the operation completes.

单项选择题Given the following steps, which would be the correct order to create a backup of an Oracle database in NOARCHIVELOG mode?（） 1.shutdown immediate from RMAN 2.Log into RMAN 3.startup mount from RMAN 4.backup database 5.alter database open 6.backup database plus archivelog delete input

A.2，3，1，4，5
B.2，1，3，6，5
C.1，3，5，4
D.2，1，3，5，6
E.2，1，3，4，5

单项选择题Given the script   create script db_backup_datafile_script  {backup datafile and 1， and2 plus archivelog delete input；} Run {execute script db_backup_datafile_script using 2；}   What is the result of running this command？（）

A. The script will fail since you instructed RMAN to back up only one datafile rather than two
B. The script will successfully back up datafile 3 without error
C. The script will fail since it uses a substitution variable which is not supported
D. The execute script command will prompt for the value of and2 since it’s not included in the command
E. The script will fail because you cannot use the plus archivelog command when backing up

单项选择题Upon starting your database, you receive the following error: You can choose from the following steps: 1.Restore the database datafiles. 2.Issue the alter database clear unarchived logfile group 1 command. 3.Issue the alter database open command. 4.Issue the alter database open resetlogs command. 5.Recover the database using point-in-time recovery. 6.Issue the Startup Mount command to mount the database. 7.Back up the database. Which is the correct order of these steps in this case?（）

A. 1,6,5,4,7
B. 6,5,4
C. 6,2,3,7
D. 1,6,3
E. The database cannot be recovered