Sorting mysql results with pagination in php - php

Question

Good morning everyone!
I've been working on a little project and I thought I was done. So, I have a bunch of pages, but I have one where there's a MYSQLi query with over 100k results, I figured it would be nice not to display all 100k+ results, so I added pagination to the site. The problem I am having is, whenever someone sorts the page and clicks next page, the sort goes away.
As I was writing this, I kind of sort of figured it out, but here's my code:
$sort = "id";
if(isset($_GET['sort'])) {
switch ($_GET['sort'] ) {
case 0:
$sort = 'id';
break;
case 1:
$sort = 'priority DESC';
break;
case 2:
$sort = 't_name';
break;
case 3:
$sort = 'loc';
break;
case 4:
$sort = 'w_req';
break;
case 5:
$sort = 'tel';
break;
case 6:
$sort = 'maint_user';
break;
}
}
// pagination
$total_results = mysqli_num_rows(mysqli_query($mysqli,"SELECT w_status FROM w_o WHERE (w_status = 'active' OR w_status = 'open') ORDER BY $sort"));
if(!isset($page_number))
$page_number = (int)$_GET['page'] <= 0 ? 1 : (int)$_GET['page']; // grab the page number
$perpage = 15; // number of elements perpage
if($page_number > ceil($total_results/$perpage))
$page_number = ceil($total_results/$perpage);
$start = ($page_number - 1) * $perpage;
$result = mysqli_query($mysqli,"SELECT * FROM w_o WHERE (w_status = 'active' OR w_status = 'open') ORDER BY $sort LIMIT $start, $perpage");
I think my issue is that $sort= "id"; and every time I click on next, the $sort gets reset to = "id" So I am thinking, maybe include the $sort in the pagination code? I appreciate any help I can get. Thank you :)
Here's the html:
<form action="re_assign_a.php" method="post" name="view_order">
<table border="0" width="100%">
<tr>
<td align="left">Previous</td>
<td align="right">Next</td>
</tr>
</table>
<br>
<table border='2' style='width: 100%; margin: auto; border-width: 1px'>
<tr>
<th><span title="More">Order #</span></th>
<th><span title="More">Priority</span></th>
<th><span title="More">Tenant Name</span></th>
<th><span title="More">Apartment</span></th>
<th><span title="More">Work Requested</span></th>
<th><span title="More">Resident Phone #</span></th>
<th><span title="More">Assigned to</span></th>
<th>Check to Re-Assign</th>
</tr>
<?php
$i = 0;
while($row = mysqli_fetch_array($result))
{
$test_id = $row['id'];
echo "<tr class='table_work'>";
echo "<td align='center'><a href='one_order.php?id=$test_id'>" . $row['id'] . "</td>";
echo
"<td align='center'><a href='one_order.php?id=$test_id'>";
if ($row['priority'] == '1') { echo "<div class='priority1'> </div>"; } elseif ($row['priority'] == '2') { echo "<div class='priority2'> </div>"; } elseif ($row['priority'] == '3') { echo "<div class='priority3'> </div>"; };
echo "</a></td>
<td align='center'><a href='one_order.php?id=$test_id'>"; echo custom_echo1 ($row['t_name']); echo "</a></td>
<td align='center'><a href='one_order.php?id=$test_id'>"; echo custom_echo1 ($row['loc']); echo "</a></td>
<td align='center'><a href='one_order.php?id=$test_id'>"; echo custom_echo($row['w_req']); echo "</a></td>";
echo "<td align='center'><a href='one_order.php?id=$test_id'>"; echo custom_echo2($row['tel']); echo "</a></td>";
echo "<td align='center'><a href='one_order.php?id=$test_id'>" . $row['maint_user'] . "</a></td>";
echo "<td align='center'><input name='assign[$i]' type='checkbox' value='" . $row['id'] . "' ></td>";
++$i;
}
?>
</table><br>
<table border="0" width="100%">
<tr>
<td align="left">Previous</td>
<td align="right">Next</td>
</tr>
</table>

Answer 1

You just need to adjust your links for going to the pages to include the sort order as a GET parameter. Store the GET parameter as a variable defaulted to zero
$sortOrder = $_GET['sort'] ? : 0;
<td align="left">Previous</td>
<td align="right">Next</td>
Now when the next or previous page link is clicked, the page number and the sort order are passed to the server.

Answer 2

You have to extend the URLs in your HTML. That's a quick & dirty solution! You have to define the variables in the code correctly.
Next page URL
<td align="left">Previous</td>
<td align="right">Next</td>
And the sort URL
<th><span title="More">Order #</span></th>