Help with explandable category tree

Posted on 16th Feb 2014 by admin

I have the below query:

SELECT l1.id as lev1_id,l2.id as lev2_id,l3.id as lev3_id,l1.category AS lev1, l2.category as lev2, l3.category as lev3
FROM categories AS l1
LEFT JOIN categories AS l2 ON l2.parentCat = l1.id
LEFT JOIN categories AS l3 ON l3.parentCat = l2.id
WHERE l1.parentCat = NULL


Which outputs something like:
-------------------------------------------------------
lev1_id | lev2_id | lev3_id |lev1 | lev2 | lev3 |
------------------------------------------------------
1 | 4 | 7 |makeup | lipstick | wet look
1 | 4 | 8 |makeup | lipstick |matt
1 | 5 | 9 |makeup | mascara| black
2 | 11 | NULL|skincare|creame | NULL
3 | 12 | 13 |haircare |hairspray| Xtra Hold

I loop through the results and list all the categories and subcategories as below.

$prevCat1Name = '';
$prevCat2Name = '';
foreach ($all_cats as $cats) {
if ($cats['lev1'] !== $prevCat1Name) {
echo $cats['lev1'];
}
if (($cats['lev2'] !== $prevCat2Name)&&($all_cat['lev2'] !== NULL)) {
echo ' - ' .$cats['lev2'];
}
if (($cats['lev3'] !== NULL)&&($all_cat['lev2'] !== NULL)) {
echo ' -- ' . $cats['lev3'] . PHP_EOL;
}

$prevCat1Name = $all_cat['lev1'];
$prevCat2Name = $all_cat['lev2'];
}

How do I amend the above code so that i can expand / contract the sublevels (without having seperate queries for each level)?

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