mysql 成绩单处理：分组排名、并列处理、确定成绩等级

    今天在做一个学校的学生成绩管理的时候，涉及到对学生的成绩进行排名的问题

    主要的难点有两处：

    1. 对不同考试项目进行分组，

    2. 对同一组内的成绩并列的要做处理，

    举个栗子：比如有两门考试

        三年级上学期语文100,100,90,80,70,60,50,0和

        三年级下学期数学100,100,99,98,98,98,97,97

    正确的结果应该是

        三年级上学期语文1,1,3,4,5,6,7,8

        三年级下学期数学1,1,3,4,4,4,7,7

    代码如下：

# 成绩排名表，所有科目，所有考试，所学学号，所有成绩
drop  TABLE if exists score_rank;
CREATE  TABLE score_rank
    SELECT id as stuid,score,rank,score_id2 as score_id
    FROM (SELECT tmp.id, tmp.score,
            @incRank := IF(@Grp = score_id,@incRank + 1,1),
            @curRank := IF(@Grp = score_id and @prevRank = score, @curRank, @incRank) AS rank,
            @prevRank := IF(@Grp = score_id,score,100),
            @Grp:=score_id as score_id2
          FROM (SELECT score_stuno as id,Score_mark as score, score_id
                  FROM score) tmp,
            (SELECT @curRank:=1, @score_id:=0,@prevRank := 100,@incRank := 0) a
          order by score_id2 asc,score desc,id asc) RESULT;

附上参考链接

1.并列处理                      

2.分组排序

另外有时候我们还需要对成绩进行等级划分，附上代码如下

drop procedure if exists proc_get_range_num;
DELIMITER //
create procedure proc_get_range_num(in in_score_id int, in is_score_type_total int)
  BEGIN
    IF (is_score_type_total=1)
      THEN
        SELECT
               sum((CASE WHEN score_mark>=295 AND score_mark <=300 THEN 1 ELSE 0 END))   A1,
               sum((CASE WHEN score_mark>=290 AND score_mark < 295 THEN 1 ELSE 0 END))   A2,
               sum((CASE WHEN score_mark>=285 AND score_mark < 290 THEN 1 ELSE 0 END))   B1,
               sum((CASE WHEN score_mark>=280 AND score_mark < 285 THEN 1 ELSE 0 END))   B2,
               sum((CASE WHEN score_mark>=270 AND score_mark < 280 THEN 1 ELSE 0 END))   C,
               sum((CASE WHEN score_mark>=260 AND score_mark < 270 THEN 1 ELSE 0 END))   D,
               sum((CASE WHEN score_mark>=0   AND score_mark < 260 THEN 1 ELSE 0 END))   E,
               sum((CASE WHEN score_mark< 0   OR  score_mark > 300 THEN 1 ELSE 0 END))   ERR
        from score WHERE score_id=in_score_id;
    ELSE
          SELECT
            sum((CASE WHEN score_mark>=95 AND score_mark <=100 THEN 1 ELSE 0 END))   A1,
            sum((CASE WHEN score_mark>=90 AND score_mark < 95  THEN 1 ELSE 0 END))   A2,
            sum((CASE WHEN score_mark>=85 AND score_mark < 90  THEN 1 ELSE 0 END))   B1,
            sum((CASE WHEN score_mark>=80 AND score_mark < 85  THEN 1 ELSE 0 END))   B2,
            sum((CASE WHEN score_mark>=70 AND score_mark < 80  THEN 1 ELSE 0 END))   C,
            sum((CASE WHEN score_mark>=60 AND score_mark < 70  THEN 1 ELSE 0 END))   D,
            sum((CASE WHEN score_mark>=0  AND score_mark < 60  THEN 1 ELSE 0 END))   E,
            sum((CASE WHEN score_mark< 0  OR  score_mark > 100 THEN 1 ELSE 0 END))   ERR
          from score WHERE score_id=in_score_id;
    END IF;
  END //
DELIMITER ;

#0,1分别表示是总分还是单科分数

call proc_get_range_num(63, 1);call proc_get_range_num(67, 0);

统计avg max min？ 还有参加考试的人数

/*****************************************************************
             proc_get_num_max_min_avg_score
 *****************************************************************/

drop procedure if exists proc_get_num_max_min_avg_score;
DELIMITER //
create procedure proc_get_num_max_min_avg_score(in in_score_id int)
  BEGIN
    SELECT
      sum(case WHEN Score_mark is NULL then 0 else 1 END ) as num,
      max(Score_mark) as max,
      min(Score_mark) as min,
      cast(avg(Score_mark) as DECIMAL(5,2)) as avg
    from score WHERE score_id=in_score_id;
  END //
DELIMITER ;