mysql - 获取最大总和为 3 列的行 - Mysql

Question

我被一些查询逻辑困住了。我有一个名为 student 的表。表中有每个学期学生的成绩。有 n 个学期。我需要获取每个学期最高分(mark1+mark2+mark3)的学生的姓名和ID。

This is my table structure

|id| name | mark1| mark2| mark3| sem|
|1 | Harry| 8    | 9    | 9    | 1  |
|2 | John | 10   | 8    | 10   | 1  |
|3 | Derek| 4    | 5    | 8    | 1  |
|4 | Dona | 8    | 9    | 5    | 1  |
|5 | Ammy | 9    | 9    | 9    | 2  |
|6 | Kate | 10   | 7    | 10   | 2  |
|7 | Aby  | 3    | 5    | 4    | 2  |
|8 | Eliza| 5    | 9    | 5    | 2  |

Needed output

|id| name | mark1| mark2| mark3| sem| maxmark|
|2 | John | 10   | 8    | 10   | 1  |   28   |
|5 | Ammy | 9    | 9    | 9    | 2  |   27   |
|6 | Kate | 10   | 7    | 10   | 2  |   27   |

MY ATTEMPT TO GET maxmark

SELECT *, (MAX(`mark1` + `mark2` + `mark3`)) AS maxmark
FROM `stud`
GROUP BY `studid`

Answer 1

此查询将为您提供您想要的结果。它将学生表与包含每个学期最高分的表连接起来，仅显示获得该学期最高分的学生 (s2.maxmark = s1.mark1+s1.mark2+s1.mark3)。

SELECT s1.*, s2.maxmark
FROM student s1
JOIN (SELECT sem, MAX(mark1 + mark2 + mark3) AS maxmark
      FROM student
      GROUP BY sem) s2
ON s2.sem = s1.sem AND s2.maxmark = s1.mark1+s1.mark2+s1.mark3

输出:

id  name    mark1   mark2   mark3   sem     maxmark
2   John    10      8       10      1       28
5   Ammy    9       9       9       2       27
6   Kate    10      7       10      2       27

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