float-pdo.php

<?php
$pdo = new PDO('mysql:dbname=floattest;host=127.0.0.1', 'root', '');

$create = $pdo->prepare('CREATE TABLE IF NOT EXISTS tbl (val DECIMAL(9,2))');
$create->execute();

$del = $pdo->prepare('DELETE FROM tbl');
$del->execute();

$ins = $pdo->prepare('INSERT INTO tbl (val) VALUES (?)');
$ins->bindValue(1, 0.5, PDO::PARAM_INT);
$ins->execute();

$sel = $pdo->prepare('SELECT * FROM tbl');
$sel->execute();
var_dump($sel->fetchColumn(0));