有如下程序：执行后的输出结果是（　　）。

A、42，42

B、23，23

C、23，42

D、42，23

What is true about sequences?（）

A、Once created, a sequence belongs to a specific schema.

B、Once created, a sequence is linked to a specific table.

C、Once created, a sequence is automatically available to all users.

D、Only the DBA can control which sequence is used by a certain table.

E、Once created, a sequence is automatically used in all INSERT and UPDATE statements.

在用户网光纤化的方案中，（）是光纤到路边的缩写。

A、FTTH

B、FTTF

C、FTTO

D、FTTC

Examine the structure of the STUDENTS table: STUDENT_ID NUMBER NOT NULL, Primary Key STUDENT_NAME VARCHAR2(30) COURSE_ID VARCHAR2(10) NOT NULL MARKS NUMBER START_DATE DATE FINISH_DATE DATE You need to create a report of the 10 students who achieved the highest ranking in the course INT SQL and who completed the course in the year 1999. Which SQL statement accomplishes this task? （）

A、SELECT student_ id, marks, ROWNUM Rank FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99 AND course_id = 'INT_SQL' ORDER BY mark DESC;

B、SELECT student_id, marks, ROWID Rank FROM students WHERE ROWID <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY mark;

C、SELECT student_id, marks, ROWNUM Rank FROM (SELECT student_id, marks FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC- 99' AND course_id = 'INT_SQL' ORDER BY mark DESC;

D、SELECT student_id, marks, ROWNUM Rank FROM (SELECT student_id, marks FROM students WHERE (finish_date BETWEEN '01-JAN-99 AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY marks DESC) WHERE ROWNUM <= 10;

E、SELECT student id, marks, ROWNUM Rank FROM (SELECT student_id, marks FROM students ORDER BY marks) WHERE ROWNUM <= 10 AND finish date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course _ id 'INT_SQL';

计算机系统包括硬件系统和软件系统，其中软件系统包括：（）。

A、系统软件

B、打印机

C、服务器

D、应用软件

E、运算器和控制器

在E-R图中，用（　　）来表示实体之间联系。

A、矩形

B、菱形

C、椭圆形

D、正方形