<div><?=(new CBXSanitizer)->sanitizeHtml($foo);?></div>

$login = $DB->ForSql($_REQUEST['login']);
$res = $DB->Query("SELECT * FROM b_user WHERE LOGIN='$login'");

$arInsert = $DB->PrepareInsert("b_user", ["LOGIN" => $_REQUEST["login"]]);
$sql = "INSERT INTO b_user (".$arInsert[0].") VALUES (".$arInsert[1].")";
$res = $DB->Query($sql);