MySQLi Array in PHP sometimes coming up empty - php

Question

Okay, so I'm pretty much at the end of my rope trying to discover the issue here, because sometimes this code works perfectly, and then sometimes not, so here it is:
$allItems = array();
$allItemsQuery = mysqli_query($conn,"SELECT * FROM cart_items WHERE crt_id='".$row['crt_id']."' AND quantity>0");
while($itemsArray = mysqli_fetch_assoc($allItemsQuery)){
array_push($allItems,$itemsArray['item_id']);
}
$allItemsNames = array();
foreach($allItems as $key => $value){
$itemNames = mysqli_fetch_assoc(mysqli_query($conn,"SELECT * FROM items WHERE id='$value'"));
array_push($allItemsNames, $itemNames['item_name']);
}
$allItemsFinal = array_combine($allItems,$allItemsNames);
$itemsList = 'Items:<br>';
foreach($allItemsFinal as $key => $value){
$itemsList .=''.$value.'<br><br>';
}
The idea is it's supposed to get all of the item ID's the user has in their cart from the DB and put it into an array, which I've established exists, grab all of the item names based on their ID, and put that into an array, and then combine the two arrays as a key and value. Then I output the data from the arrays into a string.
This code works perfectly sometimes, and then suddenly not. Can somebody give me any idea why? I'd be indebted forever.

Answer 1

I think you should throw this code away and use something like this:
$items = array();
$itemsQuery = "SELECT i.item_name, i.item_id
FROM items i WHERE i.item_id
IN (SELECT ci.item_id
FROM cart_items
WHERE crt_id='".$row['crt_id']."'
AND quantity>0
)");
$allItemsQuery = mysqli_query($conn, $itemsQuery);
while ($row = mysqli_fetch_assoc($allItemsQuery))
$items[$row['item_id']] = $items[$row['item_name']];