- trim: documentation ( source)
<?php
$related = array(1,2,3);
$sql = "SELECT id,title,pic1 FROM tbl_products WHERE id IN (";
$questionmarks = "";
for($i=0;$i<count($related);$i++)
{
$questionmarks .= "?,";
}
$sql .= trim($questionmarks,",");
$sql .= ") LIMIT 3;";
echo $sql;