若要使所有学科80分以上的成绩都增加5%, 80至60分的成绩都增加10%,应如何更新数据库( )。 A.UPDATE SC SET GRADE=GRADE*1.05 WHERE SC.GRADE>=80 UPDATE SC SET GRADE=GRADE* 1.10 WHERE SC.GRADE>=60 AND SC.GRADE <=80 B.UPDATE SC SET GRADE=GRADE* 1.10 WHERE SC.GRADE>=60 AND SC.GRADE<=80 UPDATE SC SET GRADE=GRADE* 1.05 WHERE SC.GRADE>=80 C.UPDATE SC SET GRADE=GRADE* 1.05 WIRE SC.GRADE>=80 AND SET GRADE =GRADE* 1.10 WHARE SC.GRADE>=60 D.UPDATE SC SET GRADE=GRADE* 1.10 WHERE SC.GRADE>=60 AND SC.GRADE <=80 AND SET GRADE=GRADE* 1.05 WHERE SC.GRADE>=80