题目内容
（请给出正确答案）
[主观题]
例举不能通过视图修改数据的情况
提问人：网友duomingo
发布时间：2022-01-07
如搜索结果不匹配，请 
A、create view view1 as select sno, avg(grade) from sc group by sno
B、create view view2 as select sno, sname, sdept from student where sdept='CS'
C、create view view3 as select sno, sage+20 from student where ssex='女'
D、create view view4 as select student.sno, sname, sc.sno, cno, grade from sc,student where sc.sno=student.sno and cno='1'
