How to write input content to database from PHP loop?

Question

PHP

Hello dear developers.
I apologize for this wording of the question, but I could not do it differently.
I ask for help.
There are two database tables users and deposit.
A selection of username and card is made from the users table.
It is necessary to add a text field to each selection result and at the very end one submit button.
After submitting the form, the values ​​of the text field and the username under which this field was filled should be recorded in the deposit table.
Accordingly, there are as many sample results as there are records in the deposit table.
Below is the code that makes the selection and in which you need to make changes.
I apologize in advance if the question turned out to be elementary.
I will be very grateful for your help!
I wish you success!

function getLimitedIdPath2($limit, $id){
  global $db;
  $user = mysqli_fetch_assoc(mysqli_query($db['lnk'], "SELECT * FROM `users` WHERE `id`='".$id."' LIMIT 1"));
  $chain = array();
  $i = 0;
  while(((int)$user['id'] != 0) && ($i < $limit)){
    array_unshift($chain, array($user['id'], $user['username'], $user['card']));
    $parent_id = $user['parent_id'];
    $user = mysqli_fetch_assoc(mysqli_query($db['lnk'], "SELECT * FROM `users` WHERE `id`='".$parent_id."' LIMIT 1"));
    $i++;
  } 
  return $chain;
}
  	
  $id = $_SESSION['id'];
  $limit = '11'; 
  $chain = getLimitedIdPath2($limit, $id);
             foreach($chain as $cur){
                 echo 'username: '.$cur[1];
                 echo 'card: '.$cur[2];
    }

Answer 1

Terrible code.
Well, let's say this:
foreach($chain as $cur)
And then:
foreach($_POST['arr'] as $k=>&$v)
$k - name, $v - form value.

Answer 2

You have sql injection in your code. Use PDO or prepared statements.