问题详情

已知关系模式：sc(sno, sname, grade)，各属性含义依次为学号、课程名、分数。要查找“数据库”课分数最高的学生的学号，正确的SQL语句是
A．SELECT sno FROM sc WHERE sname="数据库" AND grade=MAX(grade)
B．SELECT sno FROM sc FOR sname="数据库" OR grade＞=MAX(grade)
C．SELECT sno FROM sc WHERE sname="数据库" AND grade=(SELECT MAX(grade) FROM sc
D．SELECT sno FROM sc FOR sname="数据库" OR grade=(SELECT MAX (grade) FROM sc请帮忙给出正确答案和分析，谢谢！