多项选择题

You perform differential incremental level 1 backups of your database on each working day and level 0 backupon Sundays， to tape. Which two statements are true about differential incremental backups（）

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 1 backup.
C.The backup performed on each working day contains all the blocks that have changed since the last level 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

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多项选择题You receive complaints from users regarding the high waiting time for their transactions. Oninvestigation， you find that some users are not committing their transactions though they are notperforming any activity for a long time. As a result， SQL statements need to wait for row-level locks. Which two actions could you take to prevent this locking problem in the future（）

A.Decrease the IDLE_TIME resource limit in the profile assigned to the blocking users.
B.Use Database Resource Manager to automatically log out sessions that block others and are idle.
C.Set the limit in the profile of blocking users to control the number of blocks to be accessed in a session.
D.Decrease the maximum number of interested transaction list （ITL） slots for the segments on which the blocking user performs the transaction

多项选择题WhichtwostatementsdescribegoodpracticesforanapplicationdevelopertoreducelockingconflictsinOracledatabase（）

A.Avoid coding unnecessary long-running transactions.
B.Allow the database to handle locks in default locking mode.
C.Always explicitly code the locks as per the requirement of the application.
D.Allow escalation of row locks to block locks if too many row locks cause problem.

单项选择题User A executes the following command to drop a large table in your database： SQL> DROP TABLE trans； While the drop table operation is in progress， user B executes the following command on the same table： SQL> DELETE FROM trans WHERE tr_type=’SL’； Which statement is true regarding the DELETE command（）

A.It fails with a "Resource Busy" error.
B.It deletes the rows successfully because the table is locked in SHARE mode.
C.It fails to delete the records because the table is locked in EXCLUSIVE mode.
D.It deletes the rows successfully because the table is locked in SHARE ROW EXCLUSIVE mode.

单项选择题You suspect unauthorized data manipulation language （DML） operations on a particular table. Youwant to track users who are performing the transactions and the values used in the transactions. You alsoplan to transfer these values to another table for analysis. How would you achieve this（）

A.by using triggers
B.by using Data Pump
C.by using external tables
D.by using anonymous PL/SQL blocks

多项选择题User SCOTT executes the following command on the EMP table but has not issued COMMIT， ROLLBACK， or any data definition language （DDL） command： SQL> SELECT ename FROM emp 2 WHERE job=’CLERK’ FOR UPDATE OF empno； SCOTT has opened another session to work with the database instance. Which three operations wouldwait when issued in SCOTT’s second session（）

A.LOCK TABLE emp IN SHARE MODE；
B.LOCK TABLE emp IN EXCLUSIVE MODE；
C.UPDATE emp SET sal=sal*1.2 WHERE job=MANAGER；
D.INSERT INTO emp（empno，ename） VALUES （1289，’Harry’）；
E.SELECT ename FROM emp WHERE job=’CLERK’ FOR UPDATE OF empno；