在学生选课数据库S_T中,有: 学生表student(sno,sname,ssex,sage,sdept), 课程表course(cno,cname,cpno,ccredit), 选课表sc(sno,cno,grade)。 针对数据库S_T,以下创建视图的命令不正确的是()。
A、create view view1 as select sno,avg(grade) from sc group by snoB、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'
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'
点击查看答案