PHP - Php Access Level Control ( Permissions) Help

Below is the screenshots and script for user page level access i have used it for one of my old projects. Code is working as it was intended. But it needs to be improvised.

Users table

pages table , which has all the pages and links

Access level table. which has user id from users table and page id from pages table (for which user has access)

Once the user is created, admin gives access to the user on page basis, the permissions.php page looks like this

The modules

Menus inside the modules

Pages in each menu

Here is my code for permission.php

<div id="demo2-html">                    
<ul id="demo2" class="mnav">
	<li><a href="#">Sales</a>
    <ul>
    <li><a href="#">Lead</a>
    <ul>
			<table class="table table-bordered table-striped table-hover">
				
                <?php 
				
				$s1 = mysqli_query($con, "SELECT pages.page_id as pid, pages.code, pages.page, 
									pages.href, access_level.aid, access_level.page_id as pgid, 
									access_level.user_id 
								FROM pages
								LEFT JOIN access_level ON (pages.page_id=access_level.page_id 
									AND access_level.user_id=".$user." 
									) WHERE pages.code='led'") or die(mysqli_error($con));
									
				while($s2 = mysqli_fetch_array($s1)) {  ?>
				<tr><li><td><?php echo $s2['page']; ?>  </td><td><input type="checkbox" name="sn[]" value="<?php echo $s2['pid']; ?>" <?php if($s2['pgid'] === $s2['pid']) echo 'checked="checked"';?> />
                <input type="hidden" value="<?php echo $s2['pid']; ?>" name="page_id[<?php echo $s2['pgid']; ?>]">
                </td></li></tr>
                <?php } ?>
                </table>
				</ul>
			</li>
            
            <li><a href="#">Customer</a>
    <ul>
			
			<table class="table table-bordered table-striped table-hover">
				
                <?php 
				
				$s1 = mysqli_query($con, "SELECT pages.page_id as pid, pages.code, pages.page, 
									pages.href, access_level.aid, access_level.page_id as pgid, 
									access_level.user_id 
								FROM pages
								LEFT JOIN access_level ON (pages.page_id=access_level.page_id 
									AND access_level.user_id=".$user." 
									) WHERE pages.code='cst'") or die(mysqli_error($con));
									
				while($s2 = mysqli_fetch_array($s1)) {  ?>
				<tr><li><td><?php echo $s2['page']; ?>  </td><td><input type="checkbox" name="sn[]" value="<?php echo $s2['pid']; ?>" <?php if($s2['pgid'] === $s2['pid']) echo 'checked="checked"';?> />
                <input type="hidden" value="<?php echo $s2['pid']; ?>" name="page_id[<?php echo $s2['pgid']; ?>]">
                </td></li></tr>
                <?php } ?>
                </table>
				</ul>
			</li>
      //code goes for all the other modules
      
      </ul>
            </li>
            
    
    
</ul>
</div>


<input type="hidden" name="user" value="<?php echo $user; ?>" />
<div class="row" align="center">
<input type="submit" name="submit" class="btn btn-success" value="Save" />
  </form> 



// form Submission

if(isset($_POST['submit']))
{
	$user = $_POST['user'];
	
 $sql = "DELETE FROM access_level WHERE user_id = ".$user."";
 $query = mysqli_query($con, $sql) or die (mysqli_error($con));

foreach($_POST['sn'] as $sn)
{
 $sql = "insert into access_level (page_id, user_id) values (".$sn.", ".$user.")";
 $query = mysqli_query($con, $sql) or die (mysqli_error($con));
}


if($query)
{
header("location:users.php?access=1");	
}

	
}
  

So against each user i am storing all the page ids here. When i edit any of the users, it deletes all the records and again insers new records. Which i feel is not a proper way to do.
And also, if i have 10 users and 100 pages, suppose all the users are having access to all the pages, records in user_access table will be 1000. 

And in codewise also, i am redirecting the user to no_access.php (as below) page if the user do not have access.

<?php
ob_start();
include("connect.php");
include("admin_auth.php"); 
$q1 =  basename($_SERVER['REQUEST_URI'], '?' . $_SERVER['QUERY_STRING']);
$q2 = $_SERVER['REQUEST_URI'];
$var1 = "/".$q1;

$qa_path=explode('/', $q2);

$right_path = $qa_path[2].$var1;

$parsedUrl = parse_url($q2);


$curdir = dirname($_SERVER['REQUEST_URI'])."/";



$m4 = "select p.page_id, p.code, p.page, p.href, al.aid, al.page_id, al.user_id FROM pages p INNER JOIN access_level al ON p.page_id=al.page_id WHERE al.user_id=".$_SESSION['user_id']."";

$m5 = mysqli_query($con, $m4)  or die (mysqli_error($con));


while($nk1 = mysqli_fetch_array($m5)) {
	
	$href1[] = ($nk1['href']); }
	
	
	if(in_array($right_path, $href1)) {

echo "<script type='text/javascript'> document.location = ".BASE_URL."/".$right_path."</script>"; 
}
else
{

echo "<script type='text/javascript'> document.location = '../no_access.php' </script>";
exit();
}	

?>

I need help in improve and better/effective (structural) way to do this both in database and php script.