将 3 个 mysql 查询组合成一个查询

Question

我有一个存储学生成绩并生成学生报告的学校管理系统

一个学生要通过他，她必须有；

1. 平均60%或以上
2. 英语达到 60% 或以上
3. 在包括英语在内的 5 门科目中取得至少 60 %

我确实有查询来计算最好的 5 个科目并得出一个平均值。

但我需要我的查询能够检查及格科目的值，并计算学生已通过科目的数量（包括英语）并在一个查询中显示该信息强>

SELECT student_id, round((SUM(t.mark))/5) average_mark from (
            select marks.student_id,  ROUND(AVG(mark)) as mark  from marks
                INNER JOIN teaching_loads ON teaching_loads.id=marks.teaching_load_id
                INNER JOIN subjects ON subjects.id=teaching_loads.subject_id
            where marks.student_id = "520" AND marks.assessement_id=1  
            GROUP BY subject_id
            order by (subject_id =2) desc, mark desc
            
            LIMIT 5
            
            )t ORDER BY round((SUM(t.mark))/5) DESC

我如何构建一个查询来检查通过科目的值并计算学生已通过科目的数量（包括英语）并在一个查询中显示该信息

类似

学生编号：89 通过_主题：6 通过_subject_mark:60

在一个查询中，我希望能够获取所有数据，我该怎么做？ 请帮帮我。

以下是存储学生数据/分数的数据库及其相关表的架构。

Marks Table-Stores 学生成绩

CREATE TABLE `marks` (
  `id` bigint(20) UNSIGNED NOT NULL,
  `teacher_id` bigint(20) UNSIGNED NOT NULL,
  `student_id` bigint(20) UNSIGNED NOT NULL,
  `teaching_load_id` bigint(20) UNSIGNED NOT NULL,
  `assessement_id` bigint(20) UNSIGNED NOT NULL,
  `mark` int(11) NOT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

教学负荷

CREATE TABLE `teaching_loads` (
  `id` bigint(20) UNSIGNED NOT NULL,
  `teacher_id` bigint(20) UNSIGNED NOT NULL,
  `subject_id` bigint(20) UNSIGNED NOT NULL,
  `class_id` bigint(20) UNSIGNED NOT NULL,
  `session_id` bigint(20) UNSIGNED NOT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

科目表

CREATE TABLE `subjects` (
  `id` bigint(20) UNSIGNED NOT NULL,
  `subject_name` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `subject_type` enum('core','elective','non-value','passing_subject') COLLATE utf8mb4_unicode_ci NOT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

SQL Fiddle that has the database schema

Answer 1

由于最后一个条件，这相当棘手。所以，我在考虑窗口函数：

select student_id,
       (case when avg(mark) >= 0.6 then 'Pass'
             when avg(case when subject = 'English' then mark end) > 0.6 then 'Pass'
             when avg(case when seqnum = 5 then mark end) >= 0.6 then 'Pass'
             else 'Fail'
         end) as pass_fail
from (select m.*, subject,
             row_number() over (partition by student_id order by (subject = 'English') desc, mark desc) as seqnum
      from marks m join
           teaching_loads tl
           on tl.id = m.teaching_load_id join
           subjects s
           on s.id = tl.subject_id
     ) ms
group by student_id;

Answer 2

这行得通吗？

    select student_id,
       (case when avg(mark) >= 0.6 then 'Pass'
         when avg(case when subject = 'English' then mark end) > 0.6 then 'Pass'
         when avg(case when seqnum = 5 then mark end) >= 0.6 then 'Pass'
         else 'Fail'
     end) as pass_fail
       from (select m.*, subject,
         row_number() over (partition by student_id order by (subject = 'English') 
         desc, mark desc) as seqnum
          from marks m join
           teaching_loads tl
             on tl.id = m.teaching_load_id join
                subjects s
                  on s.id = tl.subject_id 
                   join
                    average_mark a
                    on a.student_id = marks.student_id
                    where a.average_mark > 60
            ) ms
   group by student_id;