IP协议提供哪种服务？（）

A、无连接服务

B、面向连接的服务

C、虚电路服务

D、以上都不是

 You are creating tablespaces in Oracle. Which of the following keywords or clauses permits the datafiles of a database to grow automatically in order to accommodate data growth?（）

A、DEFAULT STORAGE 

B、EXTENT MANAGEMENT 

C、AUTOEXTEND 

D、DATAFILE

View the Exhibit and examine the parameters. User A executes the following command to update the TRANS table： SQL> UPDATE B.trans SET tr_amt=tr_amt+500 WHERE c_code=’C005’；  Before user A issues a COMMIT or ROLLBACK command， user B executes the following command onthe TRANS table：  SQL> ALTER TABLE trans MODIFY （tr_type VARCHAR2（3））；  What would happen in this scenario（）

A、 The ALTER TABLE command modifies the column successfully.

B、 The DDL operation gets higher priority and transaction for user a is rolled back.

C、 The ALTER TABLE command waits indefinitely until user a ends the transaction.

D、 The ALTER TABLE command fails after waiting for 60 seconds due to the resource being busy.

You need to produce a report for mailing labels for all customers. The mailing label must have only the customer name and address. The CUSTOMERS table has these columns: Which SELECT statement accomplishes this task?（）

A、 SELECT* FROM customers;

B、 SELECT name, address FROM customers;

C、 SELECT id, name, address, phone FROM customers;

D、 SELECT cust_name, cust_address FROM customers;

E、 SELECT cust_id, cust_name, cust_address, cust_phone FROM customers;

When a database administrator chooses the dimensions for an MDC table, which two characteristics should beconsidered?（）

the query transaction rate 

numeric data versus character data  

extent size  

the cardinality of the candidate columns  

prefetch size 

Which of the following devices would allow a technician to utilize a single mouse, keyboard, and display to control numerous desktop PCs?（）

A、Port replicator

B、Docking station

C、USB hub

D、KVM switch