根据SQL标准，修改表的数据结构，下面哪种语句适用？（)A UPDATEB ALTERC CHANGED SHIFT

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

根据SQL标准，删除一个表中的记录，下面哪个语句适用？()

A DROP TABLE

B DROP

C DELETE

D ERASE

根据SQL标准，删除一个表，应该使用下面哪个语句？()

A DELETE TABLE

B DROP TABLE

C DELETE VIEW

D DROP DATABASE

根据SQL标准，创建一个表，应该使用下面哪个语句？()

A CREATE TABLE

B CREATE INDEX

C CREATE VIEW

D CREATE DATABASE

根据SQL标准，删除表student中对字段sno的唯一性约束，应该使用下面哪条语句？ ()

A drop sno from table student

B alter table student drop sno

C alter table student drop unique(sno)

D alter table student drop sno unique

A delete from student

B delete all from student

C delete * from student

D drop table student

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

A copy * from SC1 to SC2

B copy * from SC2 to SC1

C insert into SC2 select * from SC1

D insert into SC1 select * from SC2

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

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)