– 及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90 SELECT c.c_id 课程ID,c.c_name 课程NAME,MAX(s.s_score) 最高分,MIN(s.s_score) 最低分,AVG(s.s_score) 平均分, a.vv 及格率,b.cc 中等率,c.ww 优良率,d.aa 优秀率 FROM score s,course c, (SELECT a.cou/b.co vv FROM(SELECT c_id ,COUNT(c_id) cou FROM score WHERE s_score >60 GROUP BY c_id) a,(SELECT c_id ,COUNT(c_id) co FROM score GROUP BY c_id) b WHERE a.c_id=b.c_id) a, (SELECT a.cou/b.co cc FROM(SELECT c_id ,COUNT(c_id) cou FROM score WHERE s_score >=70 AND s_score <80 GROUP BY c_id) a,(SELECT c_id ,COUNT(c_id) co FROM score GROUP BY c_id) b WHERE a.c_id=b.c_id) b, (SELECT a.cou/b.co ww FROM(SELECT c_id ,COUNT(c_id) cou FROM score WHERE s_score >=80 AND s_score <90 GROUP BY c_id) a,(SELECT c_id ,COUNT(c_id) co FROM score GROUP BY c_id) b WHERE a.c_id=b.c_id) c, (SELECT a.cou/b.co aa FROM(SELECT c_id ,COUNT(c_id) cou FROM score WHERE s_score >90 GROUP BY c_id) a,(SELECT c_id ,COUNT(c_id) co FROM score GROUP BY c_id) b WHERE a.c_id=b.c_id) d WHERE s.c_id=c.c_id GROUP BY s.c_id
