Cant delete files from folder using unlink function in php - php

Question

Unable to delete file from folder otherwise code work perfectly.
same code i used for replacing or updating image where it works fine but here dosent able to delete data from folder by their id or name
if(isset($_POST['8maths_delete'])) //post method button name
{
$id = $_POST['delete_id']; //data fetch by id
$files_query = "DELETE FROM 8maths WHERE id='$id'"; //deleting data from sever
$files_query_run = mysqli_query($connection, $files_query); //query run
if($files_query_run) // query run
{
unlink("upload/".$row['files']); //unlink where upload folder where all the files held. but dosent able to delete file from folder
$_SESSION['success'] = "Your Data is Deleted"; //session for echo
header('Location: 8thmaths.php');
}
else
{
$_SESSION['status'] = "Your Data is not Deleted";
header('Location: 8thmaths.php'); //redirecting location
}
}

Answer 1

There are two issues I can see:
1 - You reference $row['files'] but I don't see $row defined anywhere in your code.
2 - Using the word 'files' I assume there could be multiple, if that's the case you need to loop over all the files and unlink them either with something like:
A foreach loop:
$result = mysqli_fetch_all($files_query_run, MYSQLI_ASSOC);
foreach($result as $row) {
unlink("upload/".$row['files']);
}
Or using a while loop.
while ($row = mysqli_fetch_assoc($files_query_run)){
unlink("upload/".$row['files']);
}
I hope this helps get you off to the right start.