PDO PHP双记录插入

Question

以下代码两次插入单个记录。

注意：

除了下面的内容之外，脚本中没有其他代码（DB_HOST，DB_NAME等常量除外）。

代码：

$dbh = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASSWORD, array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES \'UTF8\''));

$array = array(
    '2' => '13'
);

$sql = "INSERT INTO htdopen.oc_product_option (product_id, option_id, required) 
           VALUES (:product_id, :option_id, '1')";
$stm = $dbh->prepare($sql);

foreach ((array)$array as $key => $val)
{
    $stm->bindParam(':product_id', $key, PDO::PARAM_INT);
    $stm->bindParam(':option_id', $val, PDO::PARAM_INT);
    $stm->execute();

}

输出:(记录输入两次，而不是一次）

+-------------------+------------+-----------+-------+----------+
| product_option_id | product_id | option_id | value | required |
+-------------------+------------+-----------+-------+----------+
|                 1 |          2 |        13 |       |        1 |
|                 2 |          2 |        13 |       |        1 |
+-------------------+------------+-----------+-------+----------+

编辑：

我更改了代码以在屏幕和计数器上输出内容。

$dbh = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASSWORD, array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES \'UTF8\''));

$array = array(
    '2' => '13'
);

$sql = "INSERT INTO htdopen.oc_product_option (product_id, option_id, required) 
           VALUES (:product_id, :option_id, '1')";
$stm = $dbh->prepare($sql);

$c = 0;
foreach ((array)$array as $key => $val)
{
    $c++;
    echo $c . '. ' . $key .'=>'. $val . '
';

    $stm->bindParam(':product_id', $key, PDO::PARAM_INT);
    $stm->bindParam(':option_id', $val, PDO::PARAM_INT);
    $stm->execute();

}

....这是屏幕上的输出 - 单行 - 但又添加了2条记录......再次 - 很奇怪：