<?php
	$SQL = "SELECT " .
					"`des_nombre` " .
				"FROM " .
					"`des_descriptor` " .
				"WHERE " .
					"`des_pk` IN ( :values )";
	$values = "1,2,3";
	$stmt = $db->prepare($SQL);
	$stmt->bindParam(':values',$values);
	$stmt->execute();
	$return = "";
	while ($array = $stmt->fetchObject()) {
		$return .= $array->des_nombre . ", ";
	}
	echo $return;
?>