Question

Well, the weakest point of PDO is inability to debug it because prepared statements are actually stored on a server side. I spent the whole day around the problem that I cannot understand at all. So, here is the case:

//the query itself
            //Did other customers from the list buy the same style in last 3 months?
            $end = date("Y-m-d H:i:s");
            $start = strtotime("-3 month", strtotime($end));
            $start = date('Y-m-d 00:00:00', $start);
            $q = $db->prepare('SELECT COUNT(*) as totals FROM web_order
                            JOIN web_order_item ON web_order_item.od_id = web_order.od_id
                            WHERE web_order.p_vendor IN (:id)
                            AND od_pcode = :pcode
                            AND od_date BETWEEN :start AND :end
                            ');
            $q->bindValue(":pcode", '1008GD');
            $q->bindValue(":id", $custList);
            $q->bindValue(":start", $start);
            $q->bindValue(":end", $end);
            $q->execute();
            echo "SELECT COUNT(*) as totals FROM web_order
                            JOIN web_order_item ON web_order_item.od_id = web_order.od_id
                            WHERE web_order.p_vendor IN ($custList)
                            AND od_pcode = '1008GD'
                            AND od_date BETWEEN '$start' AND '$end'";
            $res = $q->fetchAll();
die(print_r($res));

And here comes the funny bit – print_r($res) prints the empty array.

Array ( [0] => Array ( [totals] => 0 [0] => 0 ) )

While echo statement with exactly the same query prints

SELECT COUNT(*) as totals FROM web_order JOIN web_order_item ON web_order_item.od_id = web_order.od_id WHERE web_order.p_vendor IN ('210','1107','2295','2452') AND od_pcode = '1008GD' AND od_date BETWEEN '2012-06-13 00:00:00' AND '2012-09-13 13:15:36'

If I execute the echoed query by itself I get ‘totals’ column to have a value of 1. At the same moment PDO statement returns nothing.

Any help will be appreciated.

UPDATE:
Although the answer was posted, I still do not get why this did not work. $custList is actually a string, not an array, because I used

$custList = implode(",", $custList);

Answer 1

As Ken mentioned in the comments on your question, your problem is the :id binding, namely, that PDO doesn’t allow you to bind an array as a param. You’ll need to loop through the array and bind the individual elements into the query.

Generally, I handle this with a foreach loop that adds a ? to the query for each element of the array, then I bind each of the elements into the query in the correct order with the other prepared variables (since ? is positional, instead of named).