【简答题】以下MySQL语句中,已知关系模式course(Cno,Cname,Cperiod,Ccredit)和stu_course(Sno,Cno,Term,Grade),在stu_course和course表中,查询选修高等数学课程的所有记录,不正确的是( )。A. SELECT * FROM course JOIN stu_course ON course.cno = stu_cour...
【简答题】在MySQL中,学生表Students中包含学号sid(主键)、姓名sname。现在查询所有有重名的学生姓名,以下语句正确的是( )。A. select sname from students group by sid having count(sid)>1; B. select sname from students group by sname having count(...