how to get data from multiple tables on sql php - php

Question

I'm currently making a table result based on PHP & mySQL, I encountered a problem where I would be pulling multiple data in tables with multiple condition, I also got error (mysqli_fetch_array() expects parameter 1 to be mysqli_result). Here are some of the codes:
<?php
include('mysql.php');
mysqli_select_db($con,"iiumsystem");
$id = $_GET['id'];
$sql = "SELECT stu_id, org_name, suv_id, stu_mark
FROM (SELECT * FROM student
INNER JOIN organization
ON org_name.stu_id = stu_id
WHERE (student.stu_id = '?' OR organization.stu_id ='?')) AS matches
INNER JOIN supervisor
ON suv_id.stu_id = stu_id
WHERE (student.stu_id = '?' OR supervisor.stu_id ='?')) AS matches
INNER JOIN mark
ON stu_mark.stu_id = stu_id
WHERE (student.stu_id = '?' OR mark.stu_id ='?')) AS matches";
$result = mysqli_query($con,$sql);
while($row = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td class='result'>".$row['stu_id']."</td>";
echo "<td class='result'>".$row['suv_id']."</td>";
echo "<td class='result'>".$row['org_name']."</td>";
echo "<td class='result'>".$row['stu_mark']."</td>";
echo "</td>";
echo "</tr>";
}
echo "</tbody>";
echo "</table>";
mysqli_close($con);
?>

Answer 1

This clearly says you have some error in your sql query.
Try to print $sql query with parameters value in and run it into any mysql client i.e. phpmyadmin. It will show you correct query error.

Answer 2

SELECT stu_id, org_name, suv_id, stu_mark FROM
(SELECT * FROM student INNER JOIN organization ON org_name.stu_id = stu_id WHERE (student.stu_id = '?' OR organization.stu_id ='?'))
AS matches
INNER JOIN supervisor ON suv_id.stu_id = stu_id
WHERE (student.stu_id = '?' OR supervisor.stu_id ='?') AS matches
INNER JOIN mark
ON stu_mark.stu_id = stu_id
WHERE (student.stu_id = '?' OR mark.stu_id ='?') AS matches
Try this. You had two extra parantheses after the WHERE statements.

Answer 3

I'm not really sure what you're trying to do here, but all of those subqueries aren't going to help you.
SELECT student.stu_id, organization.org_name, supervisor.suv_id, mark.stu_mark
FROM student
INNER JOIN organization
ON organization.stu_id = student.stu_id
INNER JOIN supervisor
ON supervisor.stu_id = student.stu_id
INNER JOIN mark
ON mark.stu_id = student.stu_id
But I'm confused about your architecture here. From what I can make out of your query, it looks like there's a one-to-many relationship between student and each of supervisor, organization, and mark. I would expect the relationship to be:
student has one supervisor
student has one organization
student has many mark
In that case, student would have a org_id and suv_id field, while mark would have a stu_id field. You would then write the query as:
SELECT student.stu_id, organization.org_name, supervisor.suv_id
FROM student
LEFT JOIN organization
ON organization.org_id = student.org_id
LEFT JOIN supervisor
ON supervisor.sup_id = student.sup_id
And I'm not sure what you want to do with mark, since I assume you would have a lot of them. AVG(mark.stu_mark) maybe?