mysql 成績單處理：分組排名、並列處理、確定成績等級

    今天在做一個學校的學生成績管理的時候，涉及到對學生的成績進行排名的問題

    主要的難點有兩處：

    1. 對不同考試項目進行分組，

    2. 對同一組內的成績並列的要做處理，

    舉個栗子：比如有兩門考試

        三年級上學期語文100,100,90,80,70,60,50,0和

        三年級下學期數學100,100,99,98,98,98,97,97

    正確的結果應該是

        三年級上學期語文1,1,3,4,5,6,7,8

        三年級下學期數學1,1,3,4,4,4,7,7

    代碼如下：

# 成績排名表，所有科目，所有考試，所學學號，所有成績
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;

附上參考鏈接

1.並列處理                      

2.分組排序

另外有時候我們還需要對成績進行等級劃分，附上代碼如下

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分別表示是總分還是單科分數

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

統計avg max min？ 還有參加考試的人數

/*****************************************************************
             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 ;