binary tree fetch the node

[manishbq]

1
            2                 3
      8          9
   10

i want pass the value in 1 node and find the left node ex 2 then find left node 8 then find the left node 10 ..!
how to possible bcoz i use the recursive function find the left node 10 but problem is not get the or store the 10 node bcoz recursive function is no return the value ....!
code is
--------------------------------------------------------
function display_children($parent) {
$result = mysql_query("SELECT * FROM digital_users WHERE parent_id='".$parent."' AND node = 'Left' ");
if(mysql_num_rows($result) > 0){
while ($row = mysql_fetch_array($result)) {
$a=$row;
display_children($row);
}
}
}
display_children(1);
-----------------------------------------

plz help ASASP...!
thanx