A．四环素 B．米诺环素 C．氯霉素 D．多西环素 E．链霉素

A. SUM(start_date)

B. AVG(start_date)

C. COUNT(start_date)

D. AVG(start_date, end_date)

E. MIN(start_date)

F. MAXIMUM(start_date)

A. Flashback logs are written sequentially, and are archived.

B. Flashback Database uses a restored control file to recover a database.

C. The Oracle database automatically creates, deletes, and resides flashback logs in the Fast RecoveryArea.

D. Flashback Database can recover a database to the state that it was in before a reset logs operation.

E. Flashback Database can recover a data file that was dropped during the span of time of the flashback.

F. Flashback logs are used to restore to the blocks‘ before images, and then the redo data may be used to roll forward to the desired flashback time.

AL100 12-JAN-2000 15 1000009-MAR-101 40 800009-MAR-102 35 1250015-MAR-103 15 12000104 25-JUN-2000 15 6000105 18-JUL-2000 20 5000106 18-JUL-2000 35 7000107 21-JUL-2000 20 650004-AUG-108 10 8000CUSTOMERSCUST_ID CUST_NAME CITY10 Smith Los Angeles15 Bob San Francisco20 Martin Chicago25 Mary New York30 Rina Chicago35 Smith New York40 Linda New YorkWhich SQL statement retrieves the order ID, customer ID, and order total for the orders that are placed on the same day that Martin places his orders?（）

A. SELECT ord_id, cust_id, ord_total FROM orders, customers WHERE cust_name=‘Mating‘ AND ord _ date IN (‘18-JUL-2000‘,‘21-JUL-2000‘);

B. SELECT ord_id, cust_id, ord_total FROM orders Where ord_date IN (SELECT ord_date FROM orders WHERE cust_id = (SELECT cust_id FROM customers WHERE cust_name = ‘MARTIN‘));

C. SELECT ord_id, cust_id, ord_total FROM orders Where ord_date IN (SELECT ord_date FROM orders, customers Where cust _ name = ‘Martin‘);

D. SELECT ord_id, cust_id, ord_total FROM orders WHERE cust_id IN (SELECT cust_id FROM customers WHERE cust name = ‘Martin‘);

Youhaveapplicationsthathavefrequentlyexecutedqueries，andproducesmallandstaticresultsets.Youconfigurethesqlnet.orafileintheclientmachinetosetanonzerovaluefortheOCI_RESULT_CACHE_MAX_SIZEparameter.Whatisthepurposeofthisconfiguration？（）

A.toavoidroundtripstotheserverbyenablingcachingofqueryresultsinclientmemory

B.toimproveperformancebystoringacopyofthedatafromtheprivateSQLareaofthePGA

C.toenhancethequeryperformancebycreatingacacheintheclientmemoryforsortingoperations

D.toavoidthestoringofqueryplansandresultsintheserverbycreatingacacheintheclientmemory

plied by the commission_pct for all employees. For records that have a NULL commission_pct, a zero must be displayed against the calculated column.Which SQL statement displays the desired results?（）

A. SELECT last_name, (salary * 12) * commission_pct FROM EMPLOYEES;

B. SELECT last_name, (salary * 12) * IFNULL(commission_pct, 0) FROM EMPLOYEES;

C. SELECT last_name, (salary * 12) * NVL2(commission_pct, 0) FROM EMPLOYEES;

D. SELECT last_name, (salary * 12) * NVL(commission_pct, 0) FROM EMPLOYEES;