ocpÌâ¿âÔõô±³£º11g-051-V9.02-µÚ184Ì⣬ÍêÕûÌâ¿âÇëµã»÷ÕâÀïÁªÏµÀÏʦ×ÉѯÁ˽â

184.Examine the structure of the STUDENTS table:

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 WHER EROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99 ANDcourse_id = 'INT_SQL' ORDER BYmarks DESC;

B. SELECT student_id, marks, ROWID "Rank" FROM students WHEREROWID <= 10 ANDfinish_date BETWEEN '01-JAN-99' AND '31-DEC-99' ANDcourse_id = 'INT_SQL' ORDER BYmarks;

C. SELECT student_id, marks, ROWNUM "Rank" FROM(SELECT student_id, marks FROM students WHEREROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99' ANDcourse_id = 'INT_SQL' ORDER BYmarks 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¡¯;

Answer: D

Ê×ÏÈÊÇROWNUMºÍROWID µÄÎÊÌâ¡£ROWID ÄÜÏÔʾ³öÕâÒ»ÐеĶÔÏóºÅ£¬ÎļþºÅ£¬ÇøºÅ£¬¿éºÅµÈ¡£ROWNUMÏÔʾÐкš£ÌâÖÐÒªÇóÏÔʾǰʮ¸öѧÉú£¬¹Ê´Ë´¦Ó¦¸ÃʹÓÃROWNUM¡£ËùÒÔB´íÎó¡£

ÌâÖÐÊ×ÏÈÒªÇó£¬ÕâЩѧÉúÖÐÔÚINT_SQL×î¸ßµÄÃû´ÎÒÔ¼°ÒªÇóʱ¼äÔÚ1999ÄÚ¡£¹Ê´Ë´¦ÐèÒªÒ»¸ö×Ó²éѯ¡£