PDO和字母数字字符串？

Question

The current error when running this from the command line is "Call to a member function bindParam() on a non-object" which I've worked out to being a problem with the variable $orderPO. Something does not like non-numeric characters which led me to the bindParam PARAM_STR business which does not work either. The database fields are both varchar 50.

My search skills are failing me. I know this must be posted somewhere about a million times but I can't seem to find it. I am completely open to doing this another way if someone has a better idea.

Current attempt code:

try
{
    $orderNum = '123456';
    $orderPO = '123456-A';


    $dbh = new PDO("mysql:host=localhost;dbname=dbname", 'someuser', 'somepass');
    $stm = $dbh->prepare("insert into some_table (order_number, order_po)");
    $stm->bindParam(':order_number', $orderNum, PDO::PARAM_STR);
    $stm->bindParam(':order_po', $orderPO, PDO::PARAM_STR);
    $stm->execute();
    print_r($stm);
    print_r($dbh);
    $arr = $stm->errorInfo();
    print_r($arr);
    $stm->closeCursor();
    $dbh = null;
}
catch(PDOException $e)
{
    echo $e->getMessage();
}

Answer 1

The correct syntax is

$stm = $dbh->prepare("insert into some_table (order_number, order_po) VALUES (?, ?)");
$stm->bindParam(1,$orderNum);
$stm->bindParam(2,$orderPO);

include the questions marks, the numbers in the bindParam call refer to which question mark you're binding the parameter to