删除视图STUDENT的命令是( )。
A.DELETE STUDENT VIEW
B.DELETE STUDETN
C.DROP STUDENT VIEW
D.DROP VIEW STUDENT
第1题:
为choose表添加外键约束,约束名为choose_student_fk,外键为student_no,连接到 student表的stuednt_no字段,以下命令正确的是______。
A.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) ;
B.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) REFERENCES student(stuednt_no);
C.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) REFERENCES student;
D.alter table choose add constraint choose_student_fk REFERENCES student(stuednt_no);
第2题:
4、为choose表添加外键约束,约束名为choose_student_fk,外键为student_no,连接到 student表的stuednt_no字段,以下命令正确的是______。
A.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) ;
B.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) REFERENCES student(stuednt_no);
C.alter table choose add constraint choose_student_fk FOREIGN KEY (student_no) REFERENCES student;
D.alter table choose add constraint choose_student_fk REFERENCES student(stuednt_no);
第3题:
有3×4的结构矩阵student,每个结构有name(姓名)、scores(分数)两个成员,其中scores是以1×5矩阵表示的5门课的成绩,那么要删除第4个学生的第2门课成绩,应采用的正确命令是()。
A.rmfield(student(1,2).scores(2))
B.rmfield(student(4).scores)
C.student(4).scores(2)=0
D.student(1,2).scores(2)=[]
第4题:
选择数据库db_student为当前数据库的命令是()
A.USE db_student;
B.OPEN db_student;
C.SELECT db_student;
D.USE DATABASE db_student;
第5题:
为choose表添加外键约束,约束名为choose_student_fk,外键为student_no,参照 student表的st_no字段,以下SQL语句片段正确的是()。
A.constraint choose_student_fk FOREIGN KEY (student_no);
B.constraint choose_student_fk FOREIGN KEY (student_no) REFERENCES student(st_no);
C.constraint choose_student_fk FOREIGN KEY (st_no) REFERENCES student(student_no);
D.constraint choose_student_fk REFERENCES student(st_no);