Question

尝试对排名进行排名，但是在第3个位置出现平局时，不给出（1,2,3,3,5 ..），而是给出（1,2,3,4,5 ...）。。请帮助下面是代码..谢谢 ................................................... ...........................

SELECT t.*
FROM (SELECT @curRank := IF(@prev= @cur, @curRank, @curRank + 1 ) AS classPosition,student_id, @prev:=@cur, @cur:=SUM(total_marks)
      FROM (SELECT m.*
            FROM marks m
            WHERE classform_name = ? AND term = ? AND academic_year = ? GROUP BY student_id
            ORDER BY SUM(total_marks) DESC
           ) n  CROSS JOIN
           (SELECT  @curRank := 0, @prev:=NULL, @cur:=NULL ) q GROUP BY student_id
     ) t 
WHERE student_id = ?

............................................... .....................

Answer 1

排名是MySQL的真正痛苦。

如果您希望在这些条件下获得单个学生的排名，我建议：

SELECT 1 + COUNT(*)
FROM marks m
WHERE m.classform_name = ? AND m.term = ? AND m.academic_year = ? AND
      m.total_marks >= (SELECT m2.total_marks
                        FROM marks m2
                        WHERE m2.classform_name = m.classform_name AND
                              m2.term = m.term
                              m2.academic_year = m.academic_year
                              m2.student_id = ?
                       );;

Answer 2

您不需要RANK函数。您始终可以按joining the table to itself对行进行排名，在这种情况下，您可以选择确定顺序（和排名）的方式。

Answer 3

我混用了session / @变量，并且聚合可能有点不可靠，但是您可以尝试将select表达式的顺序更改为 student_id, @cur:=SUM(total_marks), @curRank := IF(@prev= @cur, @curRank, @curRank + 1 ) AS classPosition, @prev:=@cur

如果这没有帮助，建议您将汇总和排名分开。实际上，您已经在子查询中求和了，所以我不确定为什么您不只是将和包括在n的结果中。

SELECT * FROM (
SELECT @curRank := IF(@prev= @cur, @curRank, @curRank + 1 ) AS classPosition, student_id, @prev:=@cur, @cur:=overall
FROM (SELECT m.*, SUM(total_marks) AS overall
    FROM marks m
    WHERE classform_name = ? AND term = ? AND academic_year = ? 
    GROUP BY student_id
    ORDER BY overall DESC
) AS n 
CROSS JOIN (SELECT  @curRank := 0, @prev:=NULL, @cur:=NULL ) AS q 
) AS completeRankings 
WHERE student_id = ?

实际上，您的原始查询应该还是有其他问题。 n仅应为每个student_id包含一个随机的total_marks值；使外部SUM毫无意义。

编辑-根据联系，位置应该可以前进到“跳过”以后的位置：

SELECT @curRank := @curRank + 1 AS counter, @prevRank := IF(@prev=@cur, @prevRank, @curRank) AS classPosition

...要从最终结果中省略counter，则必须显式扩展*。

使用SQL排名排名

3 个答案: