How to select the root node using id, parent_id?

Question

$users = $this->db->query("SELECT * FROM `users`)->rows();
$rootUser = $this->db->query("SELECT * FROM `users` WHERE id = 1")->row();

the output array is:

array(

 [0] => array(

  'id' => 1,
  'login' => 'test1',
  'parent_id' => 0

 ),
[1] => array(

  'id' => 2,
  'login' => 'test2',
  'parent_id' => 1

 ),
[2] => array(

  'id' => 3,
  'login' => 'test3',
  'parent_id' => 2

 )


)

How can I select all the nodes starting from the root node, using php, without mysql joins beacuse they have limit as far as I know only 61 joins is allowed,

Answer 1

Can you explain your question little more?

Otherwise if you mean to select only root nodes, then you can use sql below:

  SELECT * FROM `users` WHERE parent_id=0