CREATE View NPStuView AS SELECT Sno, Sname, Cno, Cname, Grade from Student, SC, Course WHERE Grade<60;< /div>
B.
CREATE View NPStuView (Sno, Sname, Cno, Cname, Grade) AS SELECT Student.Sno, Sname, Course.Cno, Cname, Grade from Student, SC, Course WHERE Student.Sno=SC.Sno and SC.Cno=Course.Cno and Grade<60;< /div>
C.
CREATE View NPStuView AS SELECT Student.Sno, Sname, Course.Cno, Cname, Grade from Student, SC, Course WHERE Student.Sno=SC.Sno and SC.Cno=Course.Cno and Grade<60;< /div>
D.
CREATE View NPStuView (Sno, Sname, Cno, Cname, Grade) SELECT Student.Sno, Sname, Course.Cno, Cname, Grade from Student, SC, Course WHERE Student.Sno=SC.Sno and SC.Cno=Course.Cno and Grade<60;< /div>
【简答题】已知: 反应① Fe (s) + CO 2 (g) FeO (s) + CO (g)的平衡常数为K 1 , 反应② Fe(s) + H 2 O (g) FeO (s) + H 2 (g)的平衡常数为K 2 , 不同温度下,K 1 、K 2 的值如下: (1)从上表可以推断:反应①是___________ (填“吸”、“放”)热反应 (2)现有反应③CO 2 (g) + H 2 (g) CO (g)...
【单选题】关于用户创建视图,下列说法正确的是( )。
【单选题】已知反应:①Fe(s)+CO 2 (g) FeO(s)+CO(g) △H=a kJ·mol -1 ;②Fe(s)+H 2 O(g) FeO(s)+H 2 (g) △H=b kJ·mol -1 。以上两个反应的平衡常数分别为K1和K2,在不同温度下,K1、K2的值如下表 下列有关叙述中正确的是 [ ]
【单选题】已知: (1)2Fe(s)+O 2 (g)=2FeO(s)△H=-544kJ?mol -1 (2)2Al(s)+ 3 2 O 2 (g)=Al 2 O 3 (s)△H=-1675kJ?mol -1 则2Al(s)+3FeO(s)=Al 2 O 3 (s)+3Fe(s)的△H为( )
【单选题】已知 FeO (S) + C (S) = CO (q) + Fe (S) 反应的 为正 , 为正,下列说法正确的是
【单选题】根据SQL标准,创建一个视图abc,通过该视图只能对表student中系dept为‘IS’的记录进行更新操作。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
【单选题】可以使用命令“net use”访问共享文件夹,输入命令正确的是( )。
C.
net use m: \\sh-svr\adv
D.
net use: administrator