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=(SELECTMAX(grade)FROMsc)

D．SELECT sno FROM sc FOR sname=”数据库”OR grade=(SELECTMAX(grade)FROMsc)