PHP MySQLi从索引中的表中选择行

So I am trying to get a auto_incremented ID from a table and put it into another table. The table I'm trying to get the ID from is a grocery list, therefore the amount of items can be added to/removed from. I'm trying to place that ID into an 'item_id' column in an inventory table.

$item_row = $connect->query("SELECT * FROM `items` WHERE **[ROW #]**=$index");
$item_ids = mysqli_fetch_assoc($item_row);
$item_id = $item_ids['id'];

$connect ->query("INSERT INTO `inventory`(`id`,`item_id`,`recipient_id`,`debtor_id`,`amount`) VALUES ('NULL','$item_id', '$user_contrib','$debtor','$price')");

The item that is selected is located in an HTML table

foreach ($item_array as $id_array){ ?>
       <td><?php echo $item_array[$index]; ?></td>
       <td> <?php echo $quantity_array[$index]; ?> </td>
       <td><?php echo $price_array[$index];
       <?php echo $id_array[$index];?>
       <form class="omb_loginForm" action="inc/contribute_item.php" method="POST">
        <input type='hidden' name='item_inventory_id' value="<?= $item_inventory_id[$index]; ?>">
        <input type='hidden' name='item_name' value="<?= $item_array[$index]?>">
        <input type='hidden' name='item_price' value="<?= $price_array[$index]?>">
        <input type='submit' name="submit" value"submit">
        </form>
        </td><?php
               $index++;
} ?></tr>

I don't know if the HMTL code will help with anything. But the item being selected is indexed.

UPDATE

I changed the first input of the form to $id_array[$index] which gets the value of the id from the items table. And then when I pass it and echo it contribute_item.php it prints, what appear to be, random letters. Both upper and lower-case. ID is an int, but would the auto_increment of the id have any affect on the format?

 <input type='hidden' name='item_id' value="<?= $id_array[$index]; ?>">

Solved it. I failed to provide code that I didn't think was necessary. In the file I declare all of the arrays I declare id_array as its own variable, but then when I run it through the for loop I was adjusting the value. I had $item_array approaching the $id_array. This was affecting the value of $id_array in the loop. So when I wanted to submit this

foreach ($item_array as $id_array) ...

I needed to change it to

foreach ($item_array as $id_arrays)...
<input type='hidden' name='item_id' value="<?= $id_array[$index]; ?>">