PIVOT table mysql with data from multiple tables - php

Question

I have a school management system, this system has to analyze data, especially student marks.
I want to be able to show student performance, in the following way;
Show a table that shows the students marks per subject as well as the student average mark and position.
Example
Position | Class | Student Average | Student Name | Geography | History | Biology | English | Math |
10 Grade11 57% John Doe 59% 40% 66% 48% 56%
11 Grade11 56% John Smith 53% 33% 56% 68% 26%
12 Grade11 55% Paul Doe 29% 30% 46% 38% 36%
This is the code I am using and it is not displaying the marks like above
SELECT
marks.student_id,
subjects.subject_name,
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
INNER JOIN grades ON grades.id=teaching_loads.class_id
WHERE
grades.stream_id = 5 AND marks.assessement_id = 1
GROUP BY
subject_id, marks.student_id
Result of above query is
The system has the following tables
Marks Table-This is the table that stores student marks
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;
Teaching Loads Table
This table is where we store the subject the teacher is teaching and in which class he/she is teaching that subject.
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;
Subjects Table
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;
Users Table
CREATE TABLE `users` (
`id` bigint(20) UNSIGNED NOT NULL,
`name` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,,
`password` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
`lastname` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`middlename` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

Answer 1

You'll have to join the marks, teaching_loads, and subjects tables multiple times, once for each subject, and calculate the row average on each row (The AVG aggregate function calculates a value across rows for the specified column). Here's an example with the first two subjects to show what I mean (this assumes all subjects for a given student are the same class):
SELECT
geog_load.class_id
,(geog.mark + hist.mark) / 2
,student.name || ' ' || student.lastname
,geog.mark
,hist.mark
FROM
users AS student
INNER JOIN marks AS geog ON geog.student_id = student.id
INNER JOIN teaching_loads AS geog_load ON geog_load.id = geog.teaching_load_id
INNER JOIN
subjects as geog_subject ON geog_subject.id = geog_load.subject_id
AND geog_subject.subject_name = 'Geography'
INNER JOIN marks AS hist ON hist.student_id = student.id
INNER JOIN teaching_loads AS hist_load ON hist_load.id = hist.teaching_load_id
INNER JOIN
subjects as hist_subject ON hist_subject.id = hist_load.subject_id
AND hist_subject.subject_name = 'History'
Then you can filter how you like with a WHERE clause, and use RANK() to show Position numbers, or whatever.