以下语句错误的是() A: LECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; B: SELECT rank, AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000 C: SELECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; D: SELECT AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000; E: SELECT rank, AVG(salary) FROM people GROUP BY rank WHERE AVG(salary) > 1000;

计算排名的函数不会是哪个? A: rank B: rank.eq C: rand D: rank.avg

‎If A and B are m × n matrices then have the same rank, then the rank of AB must equal the rank of BA.‌‎‌

Let A be an m×n matrix, then ( ). A: AAT =ATA. B: if rank(A) = m, then AT A is invertible. C: if rank(A) = n, then AAT is invertible. D: if rank(A) = n, then AT A is invertible.

The lowest naval officer rank is ______ , while the lowest army officer rank is ______ .(全部小写)

按照课程号进行分组，统计学生平均成绩大于60分的学生的信息( ) A: select cid,avg(grade) from sc group by cid having avg(grade)>60 B: select cid,avg(grade) from student group by cid having avg(grade)>60 C: select cid,avg(grade) from course where avg(grade)>60 group by cid D: select cid,avg(grade) from student where avg(grade)>60 group by cid

下面哪个语句关于GROUP BY 和HAVING语句的使用是正确的？（) A: A.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_IDHAVING AVG(SALARY) > 3000; B: B.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_ID ,DEPARTMENT_IDHAVING AVG(SALARY) > 3000; C: C.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY AVG(SALARY)HAVING AVG(SALARY) > 3000; D: D.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_ID , DEPARTMENT_IDHAVING SALARY > 3000;

按照学号进行分组，统计学生的平均成绩，且平均分按降序排列 A: select sid, avg(grade) from sc group by sid order by avg(grade) desc B: select sid, avg(grade) from sc group by cid order by avg(grade) desc C: select sid, avg(grade) from student group by sid order by avg(grade) desc D: select sid, avg(grade) from student group by cid order by avg(grade)

rank函数最常用的是求某一个数值在某一区域内的排名。rank函数语法形式:rank(number,ref,[order])，ref表示（

在ORACLE中，rank()函数和dense_rank()函数的差别是（选一项） A: rank函数和dense_rank函数都没有跳跃 B: rank函数和dense_rank函数都有跳跃 C: rank函数有跳跃 dense_rank函数没有跳跃 D: rank函数没有跳跃 dense_rank函数有跳跃