Question

I’ve created a site for users to upload their images. However, I would like to create a next image button (or previous image button). The problem is, how can I get the “next” and “previous” id’s?

The SQL structure looks like this,

CREATE TABLE IF NOT EXISTS `images` (
  `id` int(9) NOT NULL AUTO_INCREMENT,
  `user_id` int(9) NOT NULL,
  `url` varchar(450) NOT NULL,
  `upload_time` int(9) NOT NULL,
  `upload_ip` varchar(250) NOT NULL,
  `warnings` int(9) NOT NULL,
  `deleted` int(9) NOT NULL,
  PRIMARY KEY (`id`)
)

As you see, I cannot just add a “+1” because other users may get the next id etc. Is there any good easy solution for this? Maybe an example?

I’m using codeigniter, and this is how I pull out data and views a single image

PHP

// Get current image by id
function get_single_image($user_id, $image_id)
{

    $this->db->where('id', $image_id);
    $this->db->where('user_id', $user_id);
    $this->db->where('deleted', '0');

    $query = $this->db->get('images');

    if($query->num_rows() > 0)
    {

        $query = $query->result_array();
        return $query[0];

    }

    return false;

}

Answer 1

Decided to Google CodeIgniter myself for curiosity – so here’s my comment dressed up in syntax 🙂

Select the next image

$this->db->where('id >',$image_id);
$this->db->order_by('id','asc');
$this->db->limit(1);

Select the previous image

$this->db->where('id <',$image_id);
$this->db->order_by('id','desc');
$this->db->limit(1);