练习题（一）

 1.Can you drop objects from a read-only tablespace?

        A. no
        B. yes
        C. only when using the DBA role
        D. only when the tablespace is online

Answer:

2. What does the command ALTER USER scott DEFAULT ROLE NONE do?

        A. It revokes all default roles from Scott.
        B. It makes all of the roles granted to Scott default roles.
        C. It makes all of the roles granted to Scott nondefault roles.
        D. It enables Scott's currently-disabled roles for the duration of this session.
        E. It disables Scott's currently-disabled roles for the duration of this session.

Answer:

3.Two tables have a parent-child relationship that will be enforced by a primary key constraint and foreign key constraint. You would like the flexibility to insert rows in the child table before inserting rows in the parent table. What must you create to enforce the primary key constraint with a unique index?

        A. both constraints DEFERRABLE
        B. the foreign key constraints DEFERRABLE and the primary key constraint NOT DEFERRABLE
        C. both constraints NOT DEFERRABLE, and use the SET CONSTRAINT command to defer checking of the foreign key constraint as needed
        D. both constraints NOT DEFERRABLE, and use the ALTER SESSION command to defer checking of the foreign key constraint as needed
        E. the foreign key constraints DEFERRABLE, and use the ALTER TABLE command to defer checking of the foreign key constraint as needed

Answer:

4.In Oracle9i, what does the FAST_START_IO_TARGET parameter do?

        A. It allows faster access to database files.
        B. It sets targets for maximum I/O on any database file.
        C. It allows the database to distribute I/O over many disks.
        D. It improves the performance of crash and instance recovery.
Answer:

5.LGWR frequently waits on a checkpoint before performing a log switch. Which action should a DBA take?

        A. add a redo log group
        B. ALTER DATABASE NOARCHIVELOG;
        C. add additional archive processes
        D. increase the number of rollback segments
        E. increase the size of the rollback segments

Answer: