Recursive in php - php

Question

Im doing a project in php CodeIgniter which has a table where all attributes_values can be kept and it is designed such that it can have its child in same tbl. the database structure is
fld_id fld_value fld_attribute_id fld_parent_id
1 att-1 2 0
2 att-2 2 0
3 att-1_1 2 1
4 att-1_2 2 1
5 att-1_1_1 2 3
here above att-1 is the attribute value of any attribute and it has two child att-1_1 and att-1_2 with parent id 1. and att-1_1 has too its child att-1_1_1 with parent_id 3. fld_parent_id is the fld_id of the same table and denotes the child of its. Now i want to show this in tree structure like this
Level1 level2 level3 ..... level n
att-1
+------att-1_1
| +------att-1_1_1
+------att-1_2
att-2
and this tree structure can vary upto n level. the attribute values with parent id are on level one and i extracted the values from level one now i have to check the child of its and if it has further child and display its child as above. i used a helper and tired to make it recursive but it didnt happen. So how could i do it such: the code is below
foreach($attributes_values->result() as $attribute_values){
if($attribute_values->fld_parent_id==0 && $attribute_values->fld_attribute_id==$attribute->fld_id){
echo $attribute_values->fld_value.'<br/>';
$children = get_children_by_par_id($attribute_values->fld_id); //helper function
echo '<pre>';
print_r($children);
echo '</pre>';
}
}
and the helper code is below:
function get_children_by_par_id($id){ //parent id
$children = get_children($id);
if($children->num_rows()!=0){
foreach($children->result() as $child){
get_children_by_par_id($child->fld_id);
return $child;
}
}
}
function get_children($id){
$CI = get_instance();
$CI->db->where('fld_parent_id',$id);
return $CI->db->get('tbl_attribute_values');
}
please help me...............

Answer 1

The key of recursion is an "endless" call. This can be done with a function that calls it self.
So
function get_children($parent_id)
{
// database retrieve all stuff with the parent id.
$children = Array();
foreach($results as $result)
{
$result['children'] = get_children($result['id']);
$children[] = $result;
}
return $children;
}

Answer 2

Or use the SPL library built into PHP already PHP recursive iterator