Question

我有以下代码来计算关系排名。在此代码中，排名是从Mark_score的总和计算的。我想知道的是：我们如何从每个主题的mark_scored计算排名。可能有一个时间，一个学生只有一个科目失败，但他的mark_scored总和超过了通过所有科目的另一个学生的总和。因此，在这种情况下，通过所有科目的人必须排名高于获得更多总分数的人。这段代码是我到目前为止所尝试的，并且不知道如何实现我想要的。我在谷歌搜索，可能是世界上所有可用的网站，至少提供一些mysql教程但无法找到解决方案。请帮我。 Php解决方案或任何其他建议也欢迎。看我的代码：

SELECT regd, Roll_no, Name_of_Student, Section, Test_date,
       English,
       Mizo,
       Mathematics,
       SS,
       Science,
       score, fmscore, perc, Rank 
FROM 
(
  SELECT t.*, IF(@p = score, @n, @n := @n + 1) AS Rank, @p := score 
    FROM
  (
    SELECT regd, Roll_no, Name_of_Student, Test_date, Section,
            SUM(IF(Subject = 'English'    , Mark_score, 0)) English,
            SUM(IF(Subject = 'Mizo'       , Mark_score, 0)) Mizo,
            SUM(IF(Subject = 'Mathematics', Mark_score, 0)) Mathematics, 
            SUM(IF(Subject = 'SS'         , Mark_score, 0)) SS,
            SUM(IF(Subject = 'Science'    , Mark_score, 0)) Science,
            SUM(Full_mark) fmscore,
            SUM(Mark_score) score,
            SUM(Mark_score) / SUM(Full_mark) * 100 perc 
      FROM exam, (SELECT @n := 0, @p := 0) n 
     GROUP BY regd 
     ORDER BY score DESC
  ) t
) r

这是我的表：

  CREATE TABLE IF NOT EXISTS `exam` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
 `regd` int(11) NOT NULL,
 `Name_of_Student` varchar(100) COLLATE latin1_general_ci NOT NULL,
 `Class` varchar(50) COLLATE latin1_general_ci NOT NULL,
 `Roll_no` int(11) NOT NULL,
 `Section` varchar(50) COLLATE latin1_general_ci NOT NULL,
 `Name_of_exam` varchar(100) COLLATE latin1_general_ci NOT NULL,
 `Test_date` date NOT NULL,
 `Subject` varchar(50) COLLATE latin1_general_ci NOT NULL,
 `Full_mark` int(11) NOT NULL,
 `Mark_score` int(11) NOT NULL,
 `Year` year(4) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=505 ;

示例数据：

INSERT INTO `exam` (`id`, `regd`, `Name_of_Student`, `Class`, `Roll_no`, `Section`, `Name_of_exam`, `Test_date`, `Subject`, `Full_mark`, `Mark_score`, `Year`) VALUES
(1, 2147, 'Lalrinawmi', 'IX', 1, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 28, 2013),
(2, 2149, 'R.Lalruatfela', 'IX', 2, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(3, 2152, 'Lallawmtlinga', 'IX', 3, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 25, 2013),
(4, 2153, 'Malsawmdawngzela', 'IX', 4, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(5, 2154, 'Lincoln Lalduhsaka', 'IX', 5, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 22, 2013),
(6, 2157, 'Vanlalhriatpuia Hrahsel', 'IX', 6, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(7, 2158, 'C.Malsawmtluanga', 'IX', 7, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(8, 2162, 'C.M.S. Dawngliana', 'IX', 8, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 26, 2013),
(9, 2165, 'B. Malsawmkimi', 'IX', 9, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(10, 2164, 'Lalnunmawii', 'IX', 10, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 20, 2013),
(11, 2167, 'Hmangaihenlaii', 'IX', 11, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 29, 2013),
(12, 2170, 'Lalrinsangi', 'IX', 12, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 26, 2013),
(13, 2166, 'John Malsawmtluanga', 'IX', 13, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 27, 2013),
(14, 2171, 'Malsawmtluangi', 'IX', 14, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 26, 2013),
(15, 2173, 'Azid Ahmed Barbhuiya', 'IX', 15, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(16, 2174, 'John Lalramdina', 'IX', 16, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 26, 2013),
(17, 2175, 'B. Lalrotlinga', 'IX', 17, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(18, 2176, 'Rebec Lalremruati', 'IX', 18, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(19, 2177, 'Hmingthanmawii', 'IX', 19, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(20, 2178, 'Johny Lalbiakzuala', 'IX', 20, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(21, 2179, 'Lalrinfela', 'IX', 21, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(22, 2181, 'Lalremruata', 'IX', 22, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(23, 2182, 'Isaac Lalmuankima', 'IX', 23, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 20, 2013),
(24, 2185, 'Lalduhsaka', 'IX', 24, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 20, 2013),
(25, 2186, 'Lalrinfeli', 'IX', 25, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 20, 2013),
(26, 2187, 'Lalnunhlui', 'IX', 26, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 20, 2013),
(27, 2188, 'Liantinthanga', 'IX', 27, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(28, 2190, 'C.Lalmuanpuii', 'IX', 28, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 21, 2013),
(29, 2193, 'Lalramzailawma', 'IX', 29, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 23, 2013),
(30, 2194, 'Malsawmpuia', 'IX', 30, 'A', 'First Term Unit Test', '2013-07-23', 'English', 30, 26, 2013);

在一个主题中找到排名：

SELECT regd, Roll_no, Name_of_Student, Subject,
   score, Rank 
FROM 
(
  SELECT t.*, IF(@p = score, @n, @n := @n + 1) AS Rank, @p := score 
  FROM
  (
   SELECT regd, Roll_no, Name_of_Student, Subject,
        SUM(Mark_score) score
  FROM exam, (SELECT @n := 0, @p := 0) n
  Where Subject='English' 
 GROUP BY regd 
 ORDER BY score DESC
   ) t
) r

Answer 1

您想要的是使用自定义比较功能对输出进行排序。通过所有课程的所有学生的排名都高于任何一门课程失败的学生吗？这在比较功能代码中很重要。

这种使用自定义比较功能的排序可以在PHP中完成。但是，如果您可以在本地SQL方言中编写函数，那么它可能比在PHP中更快。

有关系和条件的排名

1 个答案: