哑铃形资产结构的安全性很高，很适合成熟市场。 ()此题为判断题(对，错)。

根据SQL标准，要查询表student中所有年龄age小于所有学生的平均年龄的记录，下面哪条语句适用？()

A select * from student where age< avg(age)

B select * from student having age< avg(age)

C select * from student a where a.age< (select avg(b.age) from student b)

D select * from student a where (select avg(b.age) from student b ) >= a.age

根据SQL标准，要修改表student中所有学生的年龄age，使之在原值基础上减一，下面哪个语句适用？()

A update student set age = 1

B update student set age = age - 1

C update age = age -1 from student

D update from student where age = age -1

A．SELECT TOP 3 WITH TIES 所在部门，AVG（年龄） 平均年龄 FROM 雇员表 ORDER BY 平均年龄 desc

B．SELECT TOP 3 WITH TIES 所在部门，AVG（年龄） 平均年龄 FROM 雇员表 GROUP BY 所在部门

C．SELECT TOP 3 WITH TIES 所在部门，AVG（年龄） 平均年龄 FROM 雇员表 GROUP BY 所在部门 ORDER BY 平均年龄

D．SELECT TOP 3 WITH TIES 所在部门，AVG（年龄） 平均年龄 FROM 雇员表 GROUP BY 所在部门 ORDER BY 平均年龄 DESC

A．仅Ⅰ

B．仅Ⅱ

C．Ⅰ和Ⅱ

D．Ⅱ和Ⅲ

根据SQL标准，查询表student(sno,sname,sex,dept)中所有学生的选修课程数，其中选修记录在表SC(sno,cno,grade)中，两表中sno为关联字段。下面哪条语句合适？()

A select sno,count(cno) from SC

B select sno,count(cno) from student

C select a.sno,count(cno) from student a left outer join SC

D select a.sno,count(cno) from SC left outer join student a

设有学生数据库：student(sno，sname，sex，age，dept)。现要查询所有刘姓学生的信息，可使用如下的 SQL语句：SELECT*FROM student WHERE【 】。

下面哪条语句适用？()

A create view abc as select * from student where dept=’IS’

B create view abc as select * from student where dept=’IS’ with check option

C create view abc as student where dept=’IS’

D create view abc as select dept=’IS’ from student

根据SQL标准，下面哪句语句能够找出年龄最小的同学？其中age为学生表student中的年龄字段，sno为学生的学号。()

A select max(age) from student

B select sno from student where age = max(age)

C select sno from student having age = max(age)

D select sno from student a where a.age<= (select min(b.age) from student b)

所在系DEPT 5个属性组成，其中SNO为主码），求年龄20～23岁之间的学生姓名和年龄，正确的语句是（）。A．SELECT SNAME，AGE FROM STUDENT WHERE AGE>20 AND AGE<23B． SELECT*FROM STUDENT WHERE AGE BETWEEN 20 AND 23C．SELECT SNAME，AGE FROM STUDENT WHERE AGE BETWEEN 20 AND 23D．以上均不正确