对于以下脚本……

<?PHP
    try {
        $db = new PDO('MysqL:host=localhost;dbname=db','user','pw');
        $db->setattribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
        $db->beginTransaction();

        $stmt = $db->PRepare("SELECT * From tablename");
        $stmt->execute();

        while($db->fetch(PDO_FETCH_ASSOC) as $row) {
            $id= $row['id'];
            $name= $row['name'];
        }   

        $db->commIT();
    }

    catch (PDOException $e)
    {
        $db->rollback();
        echo "There was a system error.<br>".$e->getMessage();          
    }
?>

知道什么是错误吗？我检查了丢失的分号,逗号和作品但没有得到任何结果！