sql server中查询视图

sql server中查询视图

1. 在信息系学生的视图中找到年龄<20岁的学生

select sname,sage
from is_student
where sage<20

2. 查询选修了1号课程的信息系的学生

select is_student.sno,sname 
from is_student,sc
where is_student.sno = sc.sno and sc.cno = '1'

3. 在s_g视图中查询平均成绩在90分以上的学生学号和平均成绩

select *
from s_g
where gavg>85

如果没有视图，查询语句为

select sno,avg(grade)
from sc
group by sno
having avg(grade)>85

用子查询

select *
from (
	select sno,avg(grade)
	from sc
	group by sno
	
)as s_g (sno,gavg)
where gavg > 85