how to get number of user to read post using codeigniter php

Question

I want to get number of users who read blog .

what i have done -> when user open particular post then i update blog_read column with +1 of my last value, and it works

But i have an issue if user refresh that post it will again update blog_read column with +1 of my last value, I want to update when user open post from list of post, not update on every refresh.

My code:-

public function readBlog($url)
{
    $q = $this->db->get_where('blog',array('blog_url'=>$url));

    if($q->num_rows() > 0)
    {
        foreach ($q->result() as $item)
        {
            $val = $item->blog_read;
            $val = $val+1;

            $data = array('blog_read'=>$val);

            $this->db->where('blog_url',$url);
            $this->db->update('blog',$data);
        }
    }
}

public function getBlog($url)
{   
    $this->readBlog($url);
    $q = $this->db->get_where('blog',array('blog_url'=>$url));

    if($q->num_rows() > 0)
    {
        foreach ($q->result() as $item)
        {
            $data[] = $item;
        }
        return $data;
    }
}