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Which statements are correct regarding indexes？ （）

A. When a table is dropped， the corresponding indexes are automatically dropped.
B. For each DML operation performed， the corresponding indexes are automatically updated.
C. Indexes should be created on columns that are frequently referenced as part of an expression.
D. A non-deferrable PRIMARY KEY or UNIQUE KEY constraint in a table automatically creates a uniqueindex.

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单项选择题Evaluate the following SQL statements that are issued in the given order：  What would be the status of the foreign key EMP_MGR_FK？（）

A. It would be automatically enabled and deferred.
B. It would be automatically enabled and immediate.
C. It would remain disabled and has to be enabled manually using the ALTER TABLE command.
D. It would remain disabled and can be enabled only by dropping the foreign key constraint and re-creating it.

单项选择题WhichstatementistrueregardingFlashbackVersionQuery？（）

A. It returns versions of rows only within a transaction.
B. It can be used in subqueries contained only in a SELECT statement.
C. It will return an error if the undo retention time is less than the lower bound time or SCN specified.
D. It retrieves all versions including the deleted as well as subsequently reinserted versions of the rows.

单项选择题View the Exhibit and examine the structure of the EMP table. You executed the following command to add a primary key to the EMP table：   ALTER TABLE emp   ADD CONSTRAINT emp_id_pk  PRIMARY KEY （emp_id）   USING INDEX emp_id_idx；   Which statement is true regarding the effect of the command？（）

A. The PRIMARY KEY is created along with a new index.
B. The PRIMARY KEY is created and it would use an existing unique index.
C. The PRIMARY KEY would be created in a disabled state because it is using an existing index.
D. The statement produces an error because the USING clause is permitted only in the CREATE TABLE command.

单项选择题The user SCOTT who is the owner of ORDERS and ORDERJTEMS tables issues the following  GRANT command：  GRANT ALL   ON orders， order_items   TO PUBLIC；   What correction needs to be done to the above statement？ （）

A. PUBLIC should be replaced with specific usernames.
B. ALL should be replaced with a list of specific privileges.
C. WITH GRANT OPTION should be added to the statement.
D. Separate GRANT statements are required for ORDERS and ORDERJTEMS tables.

单项选择题View the Exhibit and examine the data in ORDERS_MASTER and MONTHLYjDRDERS tables. What would be the outcome of the above statement？（）

A. The ORDERS_MASTER table would contain the ORDERJDs 1 and 2.
B. The ORDERS_MASTER table would contain the ORDERJDs 1， 2 and 3.
C. The ORDERS_MASTER table would contain the ORDERJDs 1， 2 and 4.
D. The ORDERS MASTER table would contain the ORDER IDs 1， 2， 3 and 4.