how to insert multidimensional array using for loop - php

Question

I have 2 tables. One is for students and one of subjects. I want to fetch data from the students and subjects tables on same page. In front of student 1 subject 1 subject 2 subject 3. Then in front of student 2 subject 1 subject 2 subject 3. It is to submit result.
I have done this.
Than I have to insert this in 3rd table of results. I have successfully inserted students in result table. And subjects. But on the time of marks, I am unable to insert. I used a multidimensional array. I am unable to insert marks data into array. How can I do this?
Let me show some snapshots.
My multidimensional array is not working, and I don't know how to do this. Kindly help me out.
This is a detailed pic: This is the detailed snapshot.
// count students
$sql = "SELECT * FROM tb_students";
$run = mysqli_query($mysqli,$sql);
$total_students = mysqli_num_rows($run);
$numbers=$total_students;
for($i=1;$i<=$numbers;$i++)
{
while ($rows = mysqli_fetch_assoc($run)) {
$id = $rows['student_id'];
$name = $rows['student_name'];
?>
<tr>
<td>Name</td>
<td hidden><input type="text" value="<?php echo $id?>" name="student_id[]" /></td>
<td><?php echo $name ?> </td>
</tr>
<input type="hidden" value="<?php echo $numbers;?>" name="numbers" />
<?php
$sel_sub = "SELECT * FROM subjects WHERE class_name = '1st year'";
$run_sub = mysqli_query($mysqli,$sel_sub);
$total_sub = mysqli_num_rows($run_sub);
for ($k=0; $k < $total_sub ; $k++) {
while ($rows = mysqli_fetch_assoc($run_sub)) {
$sub_id = $rows['sub_id'];
$sub_name = $rows['sub_name'];
?>
<tr>
<td><?php echo $sub_name; ?></td>
<td hidden><input type="" value="<?php echo $sub_id;?>" name="sub_id[]" /></td>
<input type="hidden" value="<?php echo $total_sub;?>" name="subject" />
<td><input type="text" name="marks[][]" placeholder="Marks" /></td>
</tr>
<?php
}
}
?>`
and this is isnert query
<?php
$mysqli = mysqli_connect("localhost","salman","salman1214","shan");
if(mysqli_connect_errno())
die("Connection failed".mysqli_connect_error());
$s = '';
for($i=0;$i<$_POST['numbers'];$i++)
{
for($j=0;$j<$_POST['subject'];$j++)
{
$s = "insert into result(student_id,exam_name, subject_name, sub_marks) values";
$s .="('".$_POST['student_id'][$i]."','".$_POST['exam_name']."','".$_POST['sub_id'][$j]."','".$_POST['marks'][$i][$j]."'),";
$s = rtrim($s,",");
if(!mysqli_query($mysqli,$s))
echo mysqli_error();
else
echo "Records Saved <br />";
$sub_list = $_POST['marks'][$i][$j];
echo $sub_list;
}
}
mysqli_close($mysqli);?>

Answer 1

I don't want to say if this way is the best way.
But, your problem is you are using the lines in the loops which should not. Try this:
<?php
$mysqli = mysqli_connect("localhost","salman","salman1214","shan");
if(mysqli_connect_errno())
die("Connection failed".mysqli_connect_error());
$s = '';
$s = "insert into result(student_id,exam_name, subject_name, sub_marks) values";
for($i=0;$i<$_POST['numbers'];$i++)
{
for($j=0;$j<$_POST['subject'];$j++)
{
$s .="('".$_POST['student_id'][$i]."','".$_POST['exam_name']."','".$_POST['sub_id'][$j]."','".$_POST['marks'][$i][$j]."'),";
}
}
$s = rtrim($s,",");
if(!mysqli_query($mysqli,$s))
echo mysqli_error();
else
echo "Records Saved <br />";
mysqli_close($mysqli);?>