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)