[eluser]Pascal Kriete[/eluser]
You can add the id to the end of your url:
example.com/blog/comments/10
And it will then be passed into your controller function as an argument.
Code:
function comments($id)
{
$query = $this->db->get_where('entries', array('id' => $id), 1, 0);
$data['query'] = $query->row_array();
}