navigation list is duplicating - php

Question

i was given help previously on how to join multiple tables together to get this navigation list to work, as you can see i have done this, but now i am trying to output the navigation in my list, but it is duplicating the top and bottom categories based on how many products are in those categories: this is previous link that shows my table setup:
Joining 2 tables with foreign key id
Here is my code trying to echo out the navigation correctly.
try
{
$result = $pdo->query('SELECT product.*, bottom_category.bottom_name, top_category.top_name
FROM product
INNER JOIN bottom_category ON bottom_category.id = product.bottom_category_id
INNER JOIN top_category ON top_category.id = bottom_category.top_category_id
ORDER BY top_category.id,bottom_category.id');
} // end try
catch (PDOException $e)
{
echo 'There was a error fetching the products.' . $e->getMessage();
exit();
} // end catch
$products = array();
foreach ($result as $row)
{
$products[] = array('top_name' => $row['top_name'],
'bottom_name' => $row['bottom_name']);
}
?>
<div class="sidebar">
<h4 class="sidebar-header">Select Products</h4>
<form class="nav-search-form">
<input type="search" name="search" placeholder="Search products">
</form>
<nav class="sidebar-links">
<ul>
<li><a id="red" href="/semtronics/index.php">New Products</a></li>
<?php
foreach ($products as $product):
?>
<li><?php echo htmlspecialchars($product['top_name']);?>
<ul>
<li><?php echo htmlspecialchars($product['bottom_name']);?></li>
</ul>
</li>
<?php endforeach; ?>
</ul>
</nav>
</div><!-- sidebar -->
Now it all works the only problem is it is duplicating the navigation list based on how many products are linked to that category.

Answer 1

I think you need another solution for this task.
You don't need product here
Query what you need is:
select bottom_category.name as bottom_name, top_category.name as top_name
from bottom_category
inner join top_category on top_category.id = bottom_category.top_category_id
order by top_category.id, bottom_category.id
I was thinking that you need something from product table in your code, but if no - use SQL query above.
Or you need data from product table ?
If you need from product you can run
select bottom_category.name as bottom_name, top_category.name as top_name
from product
inner join bottom_category on bottom_category.id = product.bottom_category_id
inner join top_category on top_category.id = bottom_category.top_category_id
group by product.bottom_category_id
order by top_category.id, bottom_category.id
But be careful, you don't know which row from product would be used in this case