多项选择题
A.The backup performed on Sundays contains all the blocks that have ever been used in the database.
B.The backup performed on Sundays contains all the blocks that have changed since the last level 1backup.
C.The backup performed on each working day contains all the blocks that have changed since the lastlevel 0 backup.
D.The backup performed on Monday contains all the blocks that have changed since the level 0 backup，and every other working day contains all the blocks that have changed since the level 1 backup.
多项选择题 You are working on a database that must be functioning 24 hours a day， 7 days a week. The databaseis configured in ARCHIVELOG mode. Which two options do you have for performing user-managed backups（）
多项选择题 You are managing an Oracle Database 11g database. The database is open， and you plan to performRecovery Manager （RMAN） backups. Which three statements are true about these backups（）
单项选择题 You executed the following command to perform a backup of the USERS tablespace： SQL> ALTER TABLESPACE users BEGIN BACKUP； ALTER TABLESPACE users BEGIN BACKUP * ERROR at line 1： ORA-01123： cannot start online backup； media recovery not enabled What could be the reason for this error（）