- rtrim: documentation ( source)
- str_repeat: documentation ( source)
- print_r: documentation ( source)
- explode: documentation ( source)
<?php
$a = '3';
$team = $a ?? '1, 2';
$terms = explode(',', $team);
print_r($terms);
$placeholders = rtrim(str_repeat('?, ', count($terms)), ', ');
echo $placeholders;