PHP MySQL code optimize -

is there mysql function optimize code? child id getting parent id

function get_parents() {  $ids = array();  while($id) :     $query = "select placement_id referrals user_id = $id";     $query = $this->db->query($query);             $result = $query->row();        if(!isset($result->placement_id)) :         break;     elseif(isset($result->placement_id) && $result->placement_id == 2) :         break;     endif;      $id = $result->placement_id;                 array_push($ids, $id);      if($result) :         continue;     endif;      break; endwhile;  return $ids;  } 

the code above return parent id of given user_id, stop if nothing found. found code slow , heavy load.

my table

relations table |   id  |   user_id |   placement_id    | |   1   |       2   |       null        | |   2   |       3   |       2           | |   3   |       4   |       2           | |   4   |       5   |       3           | |   5   |       6   |       4           | |   6   |       7   |       3           | |   7   |       8   |       3           | |   8   |       9   |       3           | |   9   |       10  |       6           | |   10  |       11  |       5           | |   11  |       12  |       6           | |   12  |       13  |       4           | |   13  |       14  |       3           | |   14  |       15  |       9           | |   15  |       16  |       10          | 

user_id child , parent placement_id

you can rewrite code as:

function get_parents() { $ids = array();  while($id){     $query = "select placement_id referrals user_id = $id";     $query = $this->db->query($query);             $result = $query->row();        if(isset($result->placement_id) && $result->placement_id !== 2)     {         $id = $result->placement_id;                     array_push($ids, $id);     } }     return $ids; } 

it excludes additional function calls such continue,break etc. also, make sure have int type of user_id indexing on column.