无法使用PDO和AJAX从数据库中删除数据

Question

我使用以下代码从数据库中删除数据。

    <?php
//include database connection
include 'connect_db.php';

try {

    $query = 'DELETE FROM tasks WHERE task_id = ?';
    $stmt = $DBH->prepare($query);
    $stmt->bindParam(1, $_POST['task_id']);
    var_dump($stmt);
    if($stmt->execute()){
        echo "Task was deleted.";
    }else{
        echo "Unable to delete Task.";
    }

}

//to handle error
catch(PDOException $exception){
    echo "Error: " . $exception->getMessage();
}
?>

但是，如果我使用以下URL调用此文件，我将获得以下内容。 数据无法删除。

~delete.php?task_id=9

object(PDOStatement)#2 (1) { ["queryString"]=> string(35) "DELETE FROM tasks WHERE task_id = ?" } Task was deleted.

Ajax功能 我使用以下ajax函数来删除数据。      //单击DELETE按钮时

   $(document).on('click', '#deleteBtn', function(){ 
            if(confirm('Are you sure?')){

                // get the id
                var task_id = $(this).closest('td').find('#task_id').text();

                // trigger the delete file
                $.post("delete.php", { id: task_id })
                    .done(function(data) {
                        // you can see your console to verify if record was deleted
                        console.log(data);

                        $('#loaderImage').show();

                        // reload the list
                        showTasks();

                    });

            }
        });