Question

我遇到了mySQL的问题，实际上我想要显示该主题中投票率最高的学生的全名。这是代码

  $query="SELECT student_tbl.fullname, student_tbl.subject, 
        COUNT(student_tbl.fullname)AS rating  
        FROM student_tbl 
        INNER JOIN subject_tbl 
        ON student_tbl.subject= subject_tbl.subjname   
        GROUP BY subject ORDER BY num, 
        COUNT(fullname) DESC";


 student_tbl                  subject_tbl
  | fullname | subject|       | subjname | num |
   ====================        ================
  | John     | Math    |      | Math     | 1   |
  | Rey      | Math    |      | Science  | 2   |
  | Wey      | Science |      | English  | 3   |
  | Xin      | Science |      =================
  | Nick     | English |
  | Mi       | English |
  | John     | Math    |
  | Xin      | Science |
  | Mi       | English | 
  ======================

这是我的代码的输出：

| fullname | Subject  | Votes |
============================
| John     | Math     |  2    |
| Wey      | Science  |  2    |
| Nick     | English  |  2    |

这是我想要的输出：

| fullname | Subject  | Votes |
============================
| John     | Math     |  2    |
| Xin      | Science  |  2    |
| Mi       | English  |  2    |

Answer 1

SELECT s1.fullname, s1.subject, COUNT(s1.fullname) AS rating  
FROM student_tbl s1
INNER JOIN subject_tbl s2
  ON s1.subject= s2.subjname   
GROUP BY subject, fullname
  HAVING COUNT(fullname) = (
    SELECT COUNT(fullname) FROM student_tbl
    WHERE s1.subject = subject
    GROUP BY fullname
    ORDER BY COUNT(fullname) DESC
    LIMIT 1
  )
ORDER BY num, COUNT(fullname)  DESC

SqlFiddle：http://sqlfiddle.com/#!2/aea20

我强烈建议您使用数字键而不是字符串键。

Answer 2

不漂亮，但它有效。我先将选票分组，然后获得排名。

SQL FIDDLE DEMO

SELECT fullname, subject, votes
FROM   (SELECT fullname,subject,votes,
             (CASE subject WHEN @curtype THEN @currow := @currow + 1 
              ELSE @currow := 1 AND @curtype := subject end ) + 1 AS rank 
        FROM   (SELECT fullname,subject,Count(1) AS Votes 
                      FROM   student_tbl 
        GROUP  BY fullname,subject) a,(SELECT @currow := 0, @curtype := '') r 
        ORDER  BY subject,votes DESC) b 
WHERE  rank = 1

MySQL - 显示最高投票

2 个答案: