Please note, that PDO format numbers according to current locale. So if, locale set number format to something else, that standard that query WILL NOT work properly.
For example:
in Polish locale (pl_PL) proper decimal separator is coma (","), so: 123,45, not 123.45. If we try bind 123.45 to the query, we will end up with coma in the query.
<?php
setlocale(LC_ALL, 'pl_PL');
$sth = $dbh->prepare('SELECT name FROM products WHERE price < :price');
$sth->bindParam(':price', 123.45, PDO::PARAM_STR);
$sth->execute();
?>